The world number one took control early on, winning the first two frames and extending his lead to 3-1, even after Murphy had compiled an impressive 131 break.
Despite Murphy's century bringing him within one frame, O'Sullivan continued his charge by registering runs of 90, 71, and 62 to seal his triumph.
The snooker legend will now await the winner of the semi-final match between Mark Allen and Ali Carter in Sunday's final.
O'Sullivan, who became the tournament's youngest winner almost 29 years ago, could now potentially become its oldest, surpassing Stuart Bingham who claimed the title at age 43 in 2020.
Reflecting on his performance, O'Sullivan acknowledged a few initial mistakes but emphasised his ability to clean up and compensate with breaks.
"At the start, there were a few mistakes but I cleaned it up a little bit - and I need to do that these days, because I can't pot as well as these guys but I can make breaks among the balls and make up for it that way," O'Sullivan told BBC Sport.
"I don't feel that old. I feel young in my mind. I feel a lot younger round the table when I play these younger players. They look old and their brains are quite slow. I still feel my brain is pretty quick round the snooker table, which is enough.
"They need to get their acts together because I am going blind, have got a dodgy arm and they still can't beat me."
While O'Sullivan dominated the latter stages of the match, Murphy had missed opportunities earlier on, including a potential counter clearance in the opener and a crucial black off its spot in the second frame. Murphy acknowledged O'Sullivan's superior performance, stating: "He was just too good - simple as that.
"I just thought Ronnie was superb and if he plays like that, you may as well give him the trophy now."
Expressing disappointment but recognising O'Sullivan's excellence, Murphy commented, "I am disappointed to lose, but I tried my best and gave everything, and it wasn't to be."
