If you are looking for a comforting slow-cooker dinner with tender pork, buttery onions, and plenty of savory gravy, this Slow Cooker Pork Tenderloin is an excellent recipe to make. The original 50K Recipes version uses two pork tenderloins layered over sliced onion, seared for color, then slow-cooked with beef broth, pork gravy mix, and butter.
This expanded version keeps that easy foundation while adding garlic, Dijon mustard, Worcestershire sauce, thyme, rosemary, and an optional cornstarch finish for an even richer onion gravy.
Because pork tenderloin is much leaner and smaller than pork shoulder, it does not need an all-day slow cook. The linked recipe cooks it on LOW for only about 2–2½ hours, using internal temperature rather than a long fixed cooking time to determine doneness.
Why You’ll Love This Slow Cooker Pork Tenderloin
The preparation is simple: onions go into the slow cooker, the pork gets a quick skillet sear, and everything finishes together with broth, gravy, and butter.
Searing is especially worthwhile because it gives the tenderloin attractive browning and deeper savory flavor without cooking it completely before it enters the slow cooker. The source specifically recommends browning all sides before slow cooking.
The tenderloin also cooks much faster than many traditional slow-cooker roasts, making this a useful recipe when you want slow-cooker convenience without starting first thing in the morning.
Finally, the cooking juices, onions, butter, and gravy mixture create an easy sauce that is perfect over mashed potatoes, rice, or roasted vegetables—the same serving direction suggested by 50K Recipes.
Ingredients
For the Pork Tenderloin
- 2 pork tenderloins, about 1 pound each
- 1 teaspoon kosher salt
- ½ teaspoon freshly ground black pepper
- 1 teaspoon garlic powder
- ½ teaspoon onion powder
- ½ teaspoon smoked paprika
- 2 tablespoons olive oil
The linked recipe starts with two approximately 1-pound tenderloins, salt, pepper, and olive oil for searing.
For the Onion Gravy
- 1 large yellow onion, thinly sliced
- 4 garlic cloves, finely minced
- ½ cup low-sodium beef broth
- 1 packet pork gravy mix
- 1 tablespoon Worcestershire sauce
- 1 tablespoon Dijon mustard
- ½ teaspoon dried thyme
- ½ teaspoon dried rosemary
- 4 tablespoons butter, thinly sliced
- ¼ teaspoon freshly ground black pepper
Onion, beef broth, pork gravy mix, and sliced butter form the core cooking mixture in the source recipe; the garlic, Worcestershire, Dijon, and herbs here are additions for a more aromatic gravy.
For a Thicker Gravy, Optional
- 1 tablespoon cornstarch
- 2 tablespoons cold water
This ratio follows the thickening option given by 50K Recipes.
For Garnishing
- Freshly chopped parsley
- Fresh thyme
- Freshly cracked black pepper
How to Make Slow Cooker Pork Tenderloin
1. Prepare the Slow Cooker
Lightly coat a 6–8-quart slow cooker with cooking spray.
Spread the thinly sliced onions across the bottom. This onion-first setup follows the linked recipe and gives the tenderloin a flavorful bed to cook over.
2. Prepare the Pork
Pat both tenderloins thoroughly dry with paper towels.
Remove any visible silver skin with a sharp knife.
Drying the exterior also makes it easier to develop good browning during the quick sear.
3. Season the Tenderloins
Combine the salt, pepper, garlic powder, onion powder, and smoked paprika.
Rub the seasoning evenly over every side of both tenderloins.
4. Heat the Skillet
Place a large skillet over medium-high heat.
Add the olive oil and allow it to become hot before adding the pork.
5. Sear the Pork
Sear one tenderloin at a time so the pan does not become overcrowded.
Brown the meat on all sides, approximately 1½–2 minutes per surface.
You are developing color rather than cooking the pork completely at this stage, which is also the purpose of the searing step in the source recipe.
6. Transfer to the Slow Cooker
Place both seared tenderloins over the sliced onions.
Keep them in a relatively even layer rather than stacking them heavily.
7. Add the Garlic
Sprinkle the minced garlic around the pork and onions.
This adds a stronger aromatic element to the simple onion-and-gravy base.
8. Add the Broth
Pour the beef broth around the pork rather than washing all of the seasoning from the top.
The linked recipe likewise uses ½ cup low-sodium beef broth for the cooking liquid.
9. Add the Gravy Seasonings
Add the pork gravy mix, Worcestershire sauce, Dijon mustard, thyme, rosemary, and black pepper.
Gently stir the liquid around the tenderloins.
10. Add the Butter
Arrange the thin slices of butter over the tenderloins.
The source recipe uses 4 tablespoons salted butter over the pork; this version uses the same amount while allowing you to control the overall salt level through the other seasonings.
11. Cover and Slow Cook
Cover the slow cooker.
Cook on LOW for approximately 2–2½ hours.
Avoid repeatedly lifting the lid. The linked recipe specifically advises keeping it closed because opening the slow cooker can extend cooking time.
12. Start Checking Early
Begin checking the pork around the 2-hour mark, especially if the tenderloins are small.
Slow cookers vary considerably in temperature, so internal temperature is far more reliable than cooking time alone.
13. Check the Internal Temperature
Insert an instant-read thermometer into the thickest part of each tenderloin.
For whole pork cuts, USDA guidance calls for a minimum internal temperature of 145°F (63°C) followed by at least a 3-minute rest.
Remove each tenderloin once it reaches the proper temperature rather than continuing to cook it for several more hours.
14. Rest the Pork
Transfer the pork to a clean cutting board.
Tent loosely with foil.
Allow it to rest for at least 3 minutes, though about 5–10 minutes works nicely before slicing. USDA specifically requires at least a three-minute rest for whole pork cuts cooked to 145°F.
15. Check the Gravy
Stir the onions and cooking juices remaining in the slow cooker.
At this stage you can serve the juices as a lighter gravy, which is how the source recipe serves the pork, or thicken them.
16. Make the Cornstarch Slurry
For thicker gravy, whisk together:
- 1 tablespoon cornstarch
- 2 tablespoons cold water
Whisk until completely smooth. This is the exact thickening proportion suggested by 50K Recipes.
17. Thicken the Gravy
Stir the slurry into the slow cooker juices.
Turn the slow cooker to HIGH.
Cook for approximately 5–10 minutes, stirring occasionally, until the sauce thickens—the same finishing method suggested by the source.
18. Adjust the Consistency
If the gravy is too thick, add a splash of warm beef broth.
If it is still thinner than you prefer, make a small additional slurry rather than adding dry cornstarch directly.
19. Slice the Pork
Slice the rested tenderloin into medallions approximately ½–¾ inch thick.
Cut across the grain.
20. Return the Juices
Pour any juices that accumulated on the cutting board back into the gravy.
Stir gently.
21. Spoon Over the Onion Gravy
Arrange the sliced pork on a serving platter.
Spoon the softened onions and rich gravy generously over the top.
22. Garnish and Serve
Finish with chopped parsley, thyme, and freshly cracked black pepper.
Serve immediately.
What to Serve With Slow Cooker Pork Tenderloin
The original 50K Recipes version recommends mashed potatoes, rice, or roasted vegetables with the pork and gravy.
For a classic comfort-food dinner, serve it over creamy mashed potatoes so the potatoes can soak up the onion gravy.
Other excellent options include:
- Buttered egg noodles
- Roasted baby potatoes
- Garlic mashed potatoes
- White or brown rice
- Creamy polenta
- Green beans
- Roasted carrots
- Broccoli
- Brussels sprouts
- Asparagus
- Warm dinner rolls
Roasted carrots and green beans are also specifically suggested as side dishes by 50K Recipes.
Tips for the Best Slow Cooker Pork Tenderloin
Make sure you are buying tenderloin, not pork loin. Tenderloin is a smaller, lean cut and cooks much faster.
Sear before slow cooking. The source recommends this for better color and flavor.
Use LOW heat. The linked recipe calls for LOW cooking and notes that this helps keep the pork tender.
Do not cook it all day. The source timing is only about 2–2½ hours on LOW.
Use a thermometer. Remove the pork once it reaches at least 145°F and give it a minimum three-minute rest.
Keep the lid closed. Repeatedly opening the slow cooker interferes with maintaining cooking temperature. The source specifically cautions against lifting the lid during cooking.
Use low-sodium broth. Pork gravy mix can already contribute plenty of seasoning.
Taste before adding additional salt.
Easy Recipe Variations
Garlic Herb Pork Tenderloin
Increase the garlic to 6 cloves and add fresh rosemary and thyme.
Garlic, rosemary, and thyme are also specifically suggested by 50K Recipes as flavor additions.
Mushroom Pork Tenderloin
Add 8 ounces sliced mushrooms over the onions before adding the pork.
They will cook down into the gravy and add extra savory flavor.
Creamy Onion Pork Tenderloin
After removing the pork, stir ½ cup heavy cream into the hot gravy.
Keep the heat gentle once the cream is added.
Dijon Garlic Pork Tenderloin
Increase the Dijon mustard to 2 tablespoons and add another 1–2 garlic cloves.
Honey Garlic Pork Tenderloin
Add 2 tablespoons honey with the broth for a subtle sweet-savory flavor.
Spicy Pork Tenderloin
Add ½ teaspoon crushed red pepper flakes or a pinch of cayenne.
Pork Tenderloin with Carrots
Add thickly sliced carrots to the onions before placing the tenderloin in the slow cooker.
Pork Loin Variation
50K Recipes lists boneless pork loin as a possible substitute but notes that the cooking time must be adjusted. Pork loin is considerably larger than tenderloin, so do not use the tenderloin timing without checking its internal temperature.
How to Store Leftovers
Allow leftover pork and gravy to cool before transferring them to airtight containers.
Refrigerate promptly and keep the pork with some gravy to help maintain moisture.
For reheating, place sliced pork and gravy in a covered skillet over low heat.
Add a splash of beef broth if the gravy has thickened too much.
Heat gently rather than aggressively boiling the pork, which helps prevent the lean tenderloin from drying out.
You can also freeze portions with the onion gravy in freezer-safe containers. Thaw overnight in the refrigerator before reheating gently.
Frequently Asked Questions
How long does pork tenderloin take in the slow cooker?
The linked 50K Recipes version cooks two approximately 1-pound tenderloins on LOW for 2–2½ hours, or until the pork reaches at least 145°F.
Can I cook pork tenderloin on HIGH?
The source says HIGH heat can shorten the cooking time, but recommends LOW for better tenderness and juiciness.
Should I sear pork tenderloin first?
It is strongly recommended.
The source sears each tenderloin on all sides specifically to develop browning before slow cooking.
What temperature should pork tenderloin reach?
USDA guidance says whole pork cuts should reach 145°F (63°C) and then rest for at least 3 minutes before carving or eating.
How do I thicken the gravy?
Mix 1 tablespoon cornstarch with 2 tablespoons cold water, stir it into the cooking juices, then heat on HIGH for approximately 5–10 minutes until thickened. That is the thickening method provided by 50K Recipes.
Can I add garlic?
Absolutely.
The original recipe specifically lists garlic cloves, rosemary, and thyme among its suggested flavor variations.
Can I use pork loin instead?
Yes, but the cooking time will be different because pork loin is a larger cut. The source lists pork loin as an alternative with adjusted cooking time.
Can I prepare it ahead?
Yes. The source notes that the pork and onion components can be prepared ahead, refrigerated, and cooked or reheated when needed.
Final Thoughts
This Slow Cooker Pork Tenderloin keeps the heart of the linked 50K Recipes dish: seared pork tenderloins cooked over sliced onions with beef broth, pork gravy, and butter until tender, then served with the flavorful cooking juices.
The expanded garlic, herbs, Dijon, and Worcestershire give the gravy even more savory depth, while the optional cornstarch slurry turns those cooking juices into a richer sauce for mashed potatoes or rice.
The most important step is avoiding the traditional all-day slow-cooker approach: begin checking around two hours and use a thermometer. Once the tenderloin reaches 145°F, give it at least a three-minute rest, slice it, and serve with plenty of warm onion gravy.