Pat the turkey breast dry with paper towels, then rub it all over with olive oil, salt, and black pepper to season evenly.
Place the turkey breast into the slow cooker, positioning it skin-side up for even cooking and maximum moisture retention.
Scatter the minced garlic over the turkey, then tuck sprigs of rosemary around the meat for fragrant aromatics.
Layer slices of orange and lemon on top of and around the turkey, which will release citrus oils during slow cooking.
Cover and set the slow cooker to low. Let it cook gently for about 8 hours until the turkey reaches an internal temperature of 165°F and becomes tender when pierced with a fork.
Once cooked, carefully transfer the turkey to a cutting board and let it rest for 10 minutes, allowing the juices to redistribute.
Slice the turkey breast against the grain into thick or thin pieces, revealing a juicy, tender interior infused with herbs and citrus.
Serve the turkey slices with a drizzle of the flavorful juices from the slow cooker for a beautifully moist presentation.