Heat the olive oil in a large deep skillet over medium-high heat.
Season the chicken with salt, pepper, paprika, oregano, and cumin. Sear until golden, about 4–5 minutes.
Stir in the onion and bell pepper. Cook until slightly softened, 3–4 minutes.
Add the garlic and cook until fragrant, about 30 seconds.
Mix in the rinsed rice and stir to coat. Toast for 1 minute.
Pour in the broth and tomatoes with juices. Scrape the pan and bring to a boil.
Reduce heat to low, cover, and simmer until rice is tender and chicken is cooked, 18–20 minutes.
Fold in the olives and spinach. Cover briefly until the greens wilt, 1–2 minutes.
Stir in lemon juice. Top with feta and parsley. Rest 5 minutes, then fluff and serve.