Walden held his nerve to reach his first significant final
World champion Ronnie O'Sullivan and qualifier Ricky Walden both staged superb fightbacks to book their places in Sunday's Shanghai Masters final.
O'Sullivan trailed Scotland's Stephen Maguire 5-4 in his semi-final but won the last two frames to snatch victory.
The Englishman produced a stunning break of 145 to win the decider.
Walden, ranked 35 in the world, came back from 4-1 behind to beat world number four Mark Selby 6-4 and reach his first major final at the age of 25.
O'Sullivan also knocked in a break of 141 and three more of over 50 in an impressive display against the world number two.
I had a bit of luck, but then I've had plenty of bad luck over my career so I think it evens itself out, but I'm happy to have some.
"I didn't play as well as I can but Stephen made it tough, so it was nice to win those last two frames and get over the line," he said.
"It was tough at times out there, I couldn't seem to find any rhythm, but my 145 in the last frame was a good way to finish the match."
Maguire said: "I had my chances, but to be honest there wasn't much I could do in those last two frames.
"It's disappointing not to have reached the final, but fair play to Ronnie because he played well, especially under pressure in those last two frames."
O'Sullivan is the clear favourite to win the best-of-19 showdown but Walden is determined to make his mark after a battling through to his first final.
The qualifier said: "I'm thrilled to bits to be in my first final but it was a real struggle out there.
"I had a bit of luck, but then I've had plenty of bad luck over my career so I think it evens itself out, but I'm happy to have some.
"To be honest, for three years in my head I've been expecting to come to events and win them, so it's good to get to a final at last."
Selby, last season's Masters and Welsh Open champion, said: "Obviously I'm very disappointed to lose from 4-1 up.
"Ricky didn't perform up to that point but after that he played a lot better."