For garnish: pomegranate arils and parsley (optional)
Preheat oven to 350° F. Pat chicken thighs dry with a paper towel, then liberally season with salt and pepper.
Heat oil in a cast-iron skillet or other large oven-proof skillet over high heat on the stove. Sear chicken thighs for 2-3 minutes per side, then remove to a clean plate. Cover and set aside.
Pour pomegranate juice and balsamic into the skillet and bring to a boil for 1 minute, then turn heat down to medium low. Whisk to deglaze the skillet and let cook until mixture has thickened, about 10-15 minutes.
Return chicken thighs to the pan with the sauce and turn to coat. Place skillet in the oven to finish cooking chicken, about 15 minutes, or until a thermometer inserted into the center reads 165° F.
Serve chicken with a drizzle of sauce from the pan and a sprinkle or pomegranate arils and parsley (optional).