Place the chicken thighs in the bottom of the slow cooker.
Add the sliced onion and minced garlic on top of the chicken.
Scatter the artichoke hearts and kalamata olives over the mixture.
Pour the chicken broth and lemon juice into the slow cooker. Sprinkle the lemon zest, oregano, thyme, salt, and black pepper evenly across the top.
Cover and cook on low for 6 hours until the chicken is tender and cooked through.
Turn off the heat and let the dish rest for 5 minutes before serving. Sprinkle with fresh parsley.