B737-800 pilot reported on takeoff aft cargo door light illuminated. Flight crew returned and landed uneventfully.

Narrative

Report for delayed communications with departure while evaluating status of Cargo Door and plan of action to return to departure airport.On takeoff roll approximately 130 knots master caution light illuminated; and the aft cargo door light was illuminated. We climbed out notified departure that we would need to return to ZZZ. We climbed to 5;000' got vectors back around for an ILS to RWY XX. We ran QRH checklist for Cargo Door light. ATC asked if we would be an overweight landing and we responded yes. Since we were not in a critical situation to return we were vectored in with traffic. We were given a discreet frequency with tower for our approach. We configured early to burn fuel and were able to land under max landing weight 146.3. We stopped after clearing the runway and had fire rescue inspect our aft cargo door. The report was it appeared to be closed. We continued to the gate and during taxi in aft cargo door light extinguished. QRH checklist was not clear as we did not know if the air pressurization system was going to pressurize as we were at low altitude. So we reviewed the steps we were below 9000' so steps didn't apply went to step XX of the checklist land at nearest suitable airport.