Taylor continued his bid to win the World Matchplay title for a 16th time with a gritty 16-14 win over King in an enthralling contest on a thrilling Friday night's action.
The Stoke legend showed all his experience and class in a fine tussle, as 50-year-old King pushed him all the way in front of a sell-out crowd.
King hit back from trailing Taylor 5-2 - after the 15-time champion landed a ten-darter in a superb opening - to level at five-all by punishing missed doubles in three successive legs from his opponent before moving 7-6 and 9-7 up.
Taylor levelled, but King held the advantage of throw to maintain the edge as the tension rose, with a 13-darter moving him 13-12 up before the 55-year-old produced the killer surge.
Another ten-darter from Taylor, featuring two 180s to tease a nine-dart finish, saw him level before a stunning 124 broke throw and moved him ahead, with another 14-darter seeing the Stoke star take a 15-13 lead.
King took out 70 on the bull to keep his hopes alive, but Taylor was too strong as he took out 66 to seal a hard-fought win and another semi-final spot.
"Mervyn played superbly," said Taylor. "That's the best I've seen Mervyn play for three or four years, he was brilliant and he put me under pressure, so fair play to him.
"It was a proper scrap and I was battling away and chasing him, but I was only ever one or two legs behind him and the 124 swung it for me.
"Towards the end I didn't know what the score was, I was concentrating so hard and just looking at my score, and when I got to 15 legs I knew I just needed one more for the match.
"The more you scrap on stage, the more the crowd feel it too and they get behind you because they can sense it, and they got their money's worth tonight.
"It won't do me any harm to have a good scrap but I missed too many doubles and I can't keep doing that because I'm making some of these games hard work. If I hit my doubles, I've got a chance of winning this but the longer it goes on I will get better."
King admitted: "I missed so many doubles early on and didn't score like I can. There were a lot of loose darts and I should have got a better result than that."
World Champion Anderson, meanwhile, held off a fine fightback from resurgent Beaton to eventually claim a 16-13 victory as he reached his second semi-final at the Winter Gardens - setting up a rematch of his classic 2014 clash with Taylor.
Beaton, the 1996 Lakeside Champion, had rolled back the years in his wins over Jelle Klaasen and Michael Smith to reach his first TV quarter-final since 2010, but saw Anderson take out 122 and 104 in an early surge to move 6-2 up.
The Scot extended that advantage to 8-3 before Beaton, inspired by a 135 bullseye finish, produced a fine run to pull back to 10-8.
Anderson punished his missed doubles to move 11-8 up, but Beaton finished 85 on the bull and 88 before levelling at 12-all by landing double ten.
Anderson, though, found a timely 177 before double six edged him back ahead, and a 70 finish on tops broke throw to move him 14-12 up before he defied an 11th maximum from Beaton to move three legs clear.
Beaton responded on double eight, but Anderson produced another 177 score before double top finally sealed his place in the last four.
"I knew it was going to be a hard game and it was, and fair play to him," said Anderson. "I got into a good lead, Steve started coming back and I started missing a few doubles - but then he missed a few and gave me my chance to win the game.
"Steve's a great guy and he likes a good laugh, but he's still a cracking dart player. If it had gone 15-all I think Steve would have gone on to win, he did great and I was fortunate to win."
Anderson added: "My record here is rubbish and Phil's going for his 16th title, so I think the pressure's on him but I'm looking forward to it. Phil's playing well and it's always special for me to play the greatest player ever."
Beaton admitted: "It was absolutely brilliant and I don't mind losing to the World Champion. I knew I had a tough game and I was a bit slow out of the blocks, and towards the end it got exciting for the crowd.
"I slipped up once or twice and he capitalised on it, and that's why he's the World Champion."
Saturday's other semi-final sees reigning champion Michael van Gerwen taking on 2013 World Matchplay finalist Adrian Lewis, meaning that the world's top four ranked players will be competing for places in the final.
World number one Van Gerwen remains the 4/7 favourite with sponsors BetVictor, with Anderson 3/1 to pick up the title, Taylor a 4/1 chance to reclaim the trophy and Lewis the 8/1 outsider to win his first Winter Gardens title.
BetVictor World Matchplay
Friday July 22
Mervyn King 14-16 Phil Taylor
Gary Anderson 16-13 Steve Beaton
Saturday July 23
Michael van Gerwen v Adrian Lewis
Gary Anderson v Phil Taylor
Best of 33 legs
4/7 Michael van Gerwen
3/1 Gary Anderson
4/1 Phil Taylor
8/1 Adrian Lewis
Semi-Final Match Odds
1/7 Michael van Gerwen v 9/2 Adrian Lewis
8/11 Gary Anderson v 11/10 Phil Taylor
Odds correct at time of writing and courtesy of www.betvictor.com. Odds subject to fluctuation.
Mervyn King v Phil Taylor
0-1 - Taylor lands the first 180 before punishing two misses from King by breaking throw immediately.
0-2 - Taylor hits another maximum before double 16 gives him a second leg.
1-2 - King gets off the mark as he lands double one.
1-3 - Taylor restores his cushion by finishing 73 on tops.
2-3 - Double eight sees King hit back again.
2-4 - Taylor produces a sparking ten-darter, scoring 180, 140 and 165 before finishing double eight.
2-5 - Taylor breaks throw with an 11-darter, scoring 140, 180 and 140 before landing double 16.
3-5 - Taylor misses a dart at double 16, and King steps in on double ten to claim his first break of throw in the game.
4-5 - Taylor lands a fifth 180, but missed doubles in two visits allow King in to reduce the gap to one leg.
5-5 - Taylor misses two darts at tops, and King pins double four to break throw again and level the match.
5-6 - Taylor is off-target with a further three misses, this time at double 12, before hitting the bed to regain the lead.
6-6 - The pair trade 180s - King with his first of the game - before Taylor's miss at the bull is punished as his opponent takes out 84 by hitting the middle double.
7-6 - Taylor's eighth 180 is followed by a second from King, who then lands tops to move ahead for the first time.
7-7 - A ninth maximum for Taylor helps him complete a 12-darter as double 16 sees him level.
8-7 - King's third 180 in a four-leg spell is followed by tops as he regains the edge.
9-7 - King lands a 174 to leave 32, and when Taylor misses two darts at double 18 the Norfolk ace steps in on double 16 to break throw again with a 13-darter and move two legs clear.
9-8 - Double 16 sees Taylor hit back with a break of throw of his own to level.
9-9 - Taylor misses a further three doubles before returning on double two - and roars as he levels the contest.
10-9 - King finishes 92 on double 16 to regain the edge.
10-10 - Taylor fires in his tenth 180 before levelling the game on double 16.
11-10 - Three further misses at tops from Taylor, to break throw, allow King back in on double eight.
11-11 - Taylor lands double ten, at the fourth time of asking, to level again.
12-11 - King misses the bull for a 126 finish, but returns to land double 16 for a 14-darter.
12-12 - Taylor takes out 60 on tops to square the match.
13-12 - Taylor lands a maximum, but King completes a 13-darter on tops.
13-13 - Taylor sets up a possible nine-darter with two 180s and adds a seventh treble 20 only to miss the treble 19 - but finishes double 16 for another ten-dart finish.
13-14 - Taylor finally claims a break of throw, taking out 124 on double 11 for a 12-darter to regain the lead in style.
13-15 - Taylor opens with his 14th 180 of the game before finishing a 14-darter on double 16 to move two legs clear and one away from the win.
14-15 - King keeps alive his hopes, taking out 70 on the bull.
14-16 - Taylor finishes 66 on double 16 to seal his place in the semi-finals.
Gary Anderson v Steve Beaton
1-0 - Anderson makes an ideal start to finish 122 on the bull to win the opener.
2-0 - The Scot doubles his lead with a break of throw.
3-0 - Double seven gives the World Champion a three-leg cushion.
3-1 - Beaton lands a third-dart double 16 to claim his first leg.
3-2 - Beaton breaks throw to reduce the gap, with both players landing 180s before a missed bull from the Scot allows him back in on tops.
4-2 - Beaton fires in his second 180, but Anderson finishes 41 on tops for another break.
5-2 - A 104 checkout sees Anderson regain a three-leg lead.
6-2 - Anderson fires in a 180 before hitting double ten to move four legs clear.
6-3 - Anderson misses his chance to open up a five-leg lead, and Beaton finishes a third-dart double eight to respond.
7-3 - Anderson regains his cushion on double 16.
8-3 - Anderson takes out 80 on tops to move five legs clear.
8-4 - Beaton finishes 78 on double 12 to respond with his first leg in three.
9-4 - Anderson takes out 60 to capitalise on a missed chance from Beaton.
9-5 - Beaton produces a sublime 135 checkout on the bull to hit back.
9-6 - Double five for Beaton sees him cut the gap to three legs.
10-6 - Anderson regains his four-leg lead.
10-7 - Two missed doubles from Anderson allow Beaton on double 16.
10-8 - Anderson fires in a 180 but misses five doubles, allowing Beaton back in on double four.
11-8 - Beaton lands two 180s, but is unable to cut the gap to one leg, with three missed doubles across two visits enabling Anderson to return on tops.
11-9 - Beaton hits his sixth 180 before double ten cuts the gap to two legs once again.
11-10 - Beaton hits another maximum before taking out 85 to reduce the arrears to one leg.
12-10 - Beaton misses his chance to level with missed darts at double four and two, with Anderson following an earlier 180 with double top.
12-11 - Both players land 180s before Beaton takes out 88 on double 14 to cut the gap once again.
12-12 - Beaton fires in a ninth maximum, and when Anderson misses one dart at double 19 the former Lakeside Champion takes out 56 on double ten to level the game.
13-12 - Beaton hits his tenth 180, but Anderson fires in a 177 to leave 24 before double six edges him back in front.
14-12 - Anderson finishes 70 on tops for a key break of throw to move two legs clear.
15-12 - Beaton fires in a 180 to leave ten, with Anderson missing double 12 and six only to see his opponent falter on double five and two, allowing the Scot back in on double six to move a leg away from the win.
15-13 - Anderson misses one match dart, at the bull, and Beaton pins double eight to keep his superb challenge alive.
16-13 - Anderson hits another 177 before tops secures an epic triumph.