Galopin Des Champs wins Cheltenham Gold Cup
Last updated on .From the section Horse Racing
Conflated was third after Ahoy Senor and Hewick, who had both looked in contention at one stage, had falls.
It came down to a duel with Galopin Des Champs coming out on top up the hill to win by seven lengths.
"It wasn't plain sailing that is for sure," a delighted Townend told ITV Racing. "Everywhere I went I was running into trouble.
"But this is a proper, proper horse because he ran three different races and still won a Gold Cup.
"I was delighted to see it all going on in front of me. It gave me a chance to fill him up after making up a lot of ground.
"This race is just different. It brings winning to a different level."
Ahoy Senor had set the pace until his mistake six from home and Townend waited patiently on the Irish Gold Cup winner before moving into contention coming down the hill.
After pulling clear with Bravemansgame, both jumped the last strongly but the Paul Nicholls-trained King George winner just did not have the pace of the winner.
It gave Mullins his 94th Festival win and his sixth of the week.
"I am feeling great, feeling emotional. It is fantastic," he told Radio 5 Live.
"We had confidence in the horse but you don't realise how much pressure that puts on you until jumping the second last and you wonder will he stay or not and he stayed. But we are delighted."
It was a second win of the day for the Mullins-Townend combination after Lossiemouth led home a 1-2-3-4 for the trainer in the Triumph Hurdle, with the first 10 horses all trained in Ireland.
Trainer Paul Nicholls celebrated his second winner of the week when 18-1 chance Stay Away Fay took a dramatic Albert Bartlett Novices' Hurdle where 150-1 outsider Afforrable Fury was second.
Favourite Corbetts Cross was in contention at the final flight but swerved right across the wing of the flight and sent jockey Mark Walsh flying.
Walsh walked away gingerly afterwards but was unable to ride in the Gold Cup and was replaced by Nico de Boinville on Minella Indo.
Prolific point-to-point winner Premier Magic, trained and ridden by Bradley Gibbs, was the biggest-priced winner of the week, winning the St James's Place Festival Challenge Cup Open Hunters' Chase at 66-1 - but there were mixed emotions for Gibbs.
"The worst part about it is my partner and my son aren't here today," he said. "We couldn't get a babysitter and my dad's in hospital having a heart operation today. It's really special but I just wish they could have been here.
"It was unbelievable, my fiancee's father owns him and we came here last year thinking we had a chance.
"I rode him down the inside and everything just got a bit tight for him, he just got stage fright really. I rode him wide today and he was a completely different horse.
"The way he's been winning his point-to-points, we always thought he was good enough to win a big race like this and it's paid off today."
It was a family affair for Bridget Andrews who won the County Hurdle on 33-1 chance Faivoir for her brother-in-law, trainer Dan Skelton, who was landing the race for the fourth time in eight years.
Stablemate Pembroke had been sent off 9-2 favourite but despite finishing down the field, jockey Harry Skelton - Bridget's husband - was among the first to congratulate her after Faivoir pipped Pied Piper by a head.
"Coming here is just a dream come true. I never thought I would be in this position," said Andrews.
Impervious battled to a well-earned success in the Mrs Paddy Power Mares' Chase, as former Champion Hurdle-winning trainer Colm Murphy returned to the Cheltenham winner's circle for the first time since 2016.
The winner got her head in front late on under Brian Hayes to maintain her unbeaten record over fences.
And the well-fancied Iroko (6-1) won the Martin Pipe Conditional Jockeys Hurdle for Aidan Kelly and trainers Oliver Greenall and Josh Guerriero to bring the curtain down on the 2023 Festival.