Gather ingredients.
Cut potatoes, onions, and celery into fairly large chunks; place in the bottom of a slow cooker along with baby carrots. Place roast on top of vegetables. Place 3 bouillon cubes randomly on top of the roast and pour in ½ cup water.
Cover and cook on Low for 6 to 8 hours or on High for 4 to 5 hours. An instant-read thermometer inserted in the thickest part of the roast should read 145 degrees F (65 degrees C).
Transfer roast to a platter. Remove vegetables using a slotted spoon and arrange them around the roast.
