He rallied from four strokes down and birdied his closing three holes to set a championship record of 22 under on the Santa da Serra course. He also set a record for lowest winning final round in the 19-year history of the event.
“I don’t have the words to describe this week as it is very emotional,” he said. “To win my first European Tour event in my own country is very special. It was a sensational round and definitely the best of my career.”
Magnus Carlsson shot 67 and was runner-up. Andreas Harto finished third, five strokes behind Santos.
Santos graduated from the Challenge Tour to the main tour this year. He earned a one-year tour exemption and an entry spot at the PGA Championship.
Former Augusta State golfer Oliver Wilson, the first round leader, shot 69 and tied for fourth.