Cessna 402/402C/B379 Businessliner/Utiliner
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence
Flight Crew Returned To Departure Airport
Aircraft; Weather
After taking off out of ZZZ; no door light illuminated. I proceeded to ZZZ1. Midway through my flight; I hit some light to moderate chop that made my rear passenger clam-shell door open. After the door opened; I slowed to 120 knots and radioed [Operations Control].  They confirmed for me to return to ZZZ.  After landing I proceeded to our fleet where I wrote the plane up.
C-402 pilot reported door opening in flight.