The Welsh left-hander, who won the 2008 Lakeside Championship, booked his place in the final at the Doncaster Dome with another assured display as he chases the £60,000 first prize.
He hit 180s in winning the first two legs before posting double ten in the third to leave Newton reeling at 3-0 down.
The Fleetwood ace hit tops to get off the mark in the fourth, and hit scores of 177 and 180 in the next to set up a potential nine-darter.
Although he was unable to achieve a perfect leg, he took out 86 for a 12-dart finish to pull back to 3-2.
Webster, though, hit a 168 to set up double ten in winning the sixth, and added tops to lead 5-2 before Newton posted two 180s and double 16 to reply.
The pair traded 180s in the ninth, with Webster’s maximum leaving 67 but only able to watch as Newton produced a 138 checkout on double nine to pull back to 5-4.
He was crucially unable to level, though, with Webster hitting double ten to edge away and 180 in setting up double nine to lead 7-4.
Newton hit double ten to win two of the next three legs, but a miss at tops for a 110 finish allowed Webster to move a leg away from victory at 9-6.
Webster would miss tops in the next, for a 106 finish, as Newton posted double eight to stay in the contest, but even a 180 from the UK Open runner-up was not enough to continue the fightback as the Welshman sealed victory on double ten.
“My finishing was pretty sharp and I’m delighted to be through,” said Webster. “I had a little bit of luck but I’ve not beaten Wes for a while so it’s nice to end that run.
“Hopefully I can go on to win the final now.”
Newton admitted: “It’s disappointing for me and I felt that the little things didn’t go my way and I wasn’t able to gain any momentum. I came back into it after the start, but Mark did well and never let me get on level terms.”