The former world number one, 56, last won the tournament in 2014, but earned a 17-9 victory in front of a raucous crowd at Blackpool's Winter Gardens.
He faces Peter Wright, who beat Daryl Gurney 17-15, in Sunday's final.
"It's my last day here tomorrow and I'm going out with a bang," said Taylor, who is retiring at the end of the year.
Englishman Taylor continued his fine form after thrashing Dutch world number one Michael van Gerwen in the quarter-finals on Friday.
It was 32-year-old Lewis, also of England, who broke first and took a 3-1 lead, but Taylor came back almost instantly to level the match at 3-3.
Despite his superior average going into the second interval, Taylor only led 8-7 with the throw.
But in a repeat of the 2013 final, in which Taylor beat Lewis 18-13, the 15-time champion became the more dominant player as the match progressed.
With Lewis starting to make more mistakes, Taylor raced away to victory.
Taylor told Sky Sports: "My mindset was keep him under pressure and that he will feel it in the last part of the game.
"I knew he was shattered and I had to take advantage, even though I love him."
Wright is through to his first final at the World Matchplay and a win over Taylor would be the biggest prize of the 47-year-old Scot's professional career so far.
He will be looking to improve on his average of 93 in a heated semi-final against Northern Ireland's Gurney, which included some verbal exchanges between the two players.
"We had a little argy-bargy on stage. I was getting grief from the crowd, he wasn't. Then he said something to me when I walked past," Wright told Sky Sports.
"I got over the line anyway and I'm in the final. I'm one game away."
The World Matchplay is considered the second biggest tournament in the sport, after the World Championship.
Phil Taylor produced a brilliant semi-final display to beat Adrian Lewis and stay on course for his 16th World Matchplay title.