The Omega Pharma QuickStep rider romped home to take stage five in a time of 3:11.11 from Yauheni Hutarovich of Belarusian as he stretched his lead at the event.
Cavendish thrived on the 154km stage from Al Zubara Fort to Madinat Al Shamal, and pipped Hutarovich and Orica-GreenEdge’s Aidis Kruopis in the final stages.
Cavendish’s team provided him with a perfect lead-out with Niki Terpstra dropping off the sprinter’s shoulder inside the final 250m.
"The team did this after riding for me the whole day," Cavendish said. "The last two days of course we wanted the big commitment, but we really got out the unit today. We just rode incredible as a unit.
"Some other teams tried to take over — I think they got some confidence in the last few days. But my entire team came to me in the last minute and we just went."
The Brit now leads the race from Brent Bookwalter by 15 seconds, having taken the overall lead on stage four.