Aided by a brilliant maximum break of 147 in the eighth frame, Trump fought back from 6-1 down to trail 7-6 in the best-of-19 final in Bolton.
However, seven-time world champion O'Sullivan then reeled off the next three frames to seal a 10-6 victory and claim the first prize of £150,000.
"Even when I was 6-1 up I never once thought about the lead because I know what Judd is like, he can come out and do what he done, pull me back to 7-6, but I was just pleased how I dug in at the end there," O'Sullivan told ITV4.
"I'm not as hungry as probably all the other players are, I'm just happy to be here, I like to compete. I just take every match as it comes, I enjoy being out here and it's like a holiday for me."
Trump did not score a point in the first two frames as O'Sullivan made breaks of 96 and 103 on his way to a seemingly commanding 6-1 lead, but Trump then brought the capacity crowd to their feet after potting 15 reds, 15 blacks and the six colours in the eighth frame.
The former world champion, who also made a 147 in the final of the inaugural Turkish Masters in March, took the last frame of the session with a 96 clearance and although O'Sullivan began the evening session with a century, he did not pot a single ball in the next three frames.
Breaks of 82 and 100 helped Trump reduce his deficit to a single frame, only for O'Sullivan to respond brilliantly with contributions of 124, 85 and 81 to wrap up victory.
Asked about his 147, Trump said: "It's always special to make them and even more special in a final against Ronnie. It's another thing ticked off the CV but obviously I'm disappointed to lose.
"I thought Ronnie scored very heavy the whole day so it puts you under pressure. Any time you get a chance you have to clear up in one visit and I didn't do that enough."