It has undoubtedly been the finest season of Murray’s career, but it would have had a bitter ending had he not walked away with the trophy at London’s O2 Arena.
Instead, he defied the tiredness he must have felt to stamp his authority on proceedings against the man whom he overhauled two weeks ago, and won 6-3 6-4.
It extended Murray’s winning run to 24 matches, earned him a fifth straight title and a cheque for nearly £2m.
This was the first time the No 1 ranking had been decided on the final match of the season and it was hard to disagree when Djokovic described the contest as one of the biggest they will ever play.
Their 34 previous meetings, of which Djokovic had won 24, had included seven grand slam finals, but this was a uniquely tense occasion.
What would have been a 50/50 contest appeared to have swung Djokovic’s way when Murray was detained for three hours and 38 minutes by Milos Raonic in Saturday’s semi-finals. The Serbian, meanwhile, needed little more than an hour to swat aside Kei Nishikori, who was still feeling the effects of his own three-hour clash with Murray on Wednesday.
Sheer willpower cannot put a spring back in muscles clogged up with lactate or freshen up a mind frazzled by the demands of an 11-month season.
Murray’s previous victories against Djokovic had come when he successfully trod the fine line between aggression and patience.
But even in the first set of his clash with Raonic he was half a step slow and struggling to push up into his forehand.
Djokovic, meanwhile, jogged to the net after what amounted to no more than a light workout against Nishikori.
He may have arrived in London with the weight of the world on his shoulders, but a venue that has brought him so much success had this time helped him restore form and confidence.
However, this was by far his biggest test of the week, and it did not take long for the problems of the last few months to come seeping back.
Djokovic’s groundstrokes lacked their usual authority and he was missing routine shots – not least a smash from on top of the net that he drove way long. That came in a lengthy sixth game in which Murray held two break points.
Djokovic held on that time, but Murray was given another chance two games later and took it, drilling a forehand into the corner.
The Scot was treading the line perfectly, going for his shots, particularly on the forehand, but not giving away free points.
He was leaving that to Djokovic, who netted another backhand on set point and then dropped serve again to start the second set.
Murray had never beaten the man he first played in junior tennis nearly 20 years ago from a set down, losing all 19 matches, so the early advantage was crucial.
There appeared no way back when a lacklustre Djokovic was broken again to trail 4-1, but an immediate break back set home nerves jangling a little.
Murray, though, quelled the butterflies and, amid a patriotic din, took his third match point when Djokovic drove a final forehand wide.
Murray dropped his racket and held his arms aloft with a look of mild astonishment on his face before embracing Djokovic at the net.
After collecting the tournament and No 1 trophies, he said: “Obviously it’s a very special day. Playing against Novak in a match like this – we’ve played grand slam finals, Olympics, it’s been a tough rivalry.
“I’ve lost many of them, I’m very happy I managed to win today. To finish the year No 1 is something I never expected.”
When Djokovic beat Murray to win the French Open and hold all four grand slam trophies, it seemed inconceivable he would not finish the year No 1.
But he has won only one tournament since and has a lot of work to do if he is to rediscover top form.
The 29-year-old said: “It’s been a fantastic year. Obviously there’s a lot to look back to, great highlights, especially in the first six months.
“Today we were both part of history, it was an honour to be on the court. Andy is clearly No 1 of the world, he’s the best player.
“He played the best tennis in the decisive moments. I wasn’t able to come back. I started playing a bit better but it was too late. I congratulate Andy and his team for a great year.”
Jamie Murray could not make it a family double as he and Bruno Soares suffered a disappointing defeat in the doubles semi-finals.
Murray and Soares were guaranteed to finish the year as the world’s No 1 doubles team after defeat for Nicolas Mahut and Pierre-Hugues Herbert on Friday.
But, after three victories in their round-robin matches, they were outplayed by South Africa’s Raven Klaasen and Rajeev Ram of the US and went down 6-1 6-4 in exactly an hour.
Judy Murray posted a picture of her two sons on Twitter, captioned with the words ‘Andy & Jamie Murray: Pride of Scotland, Kings of world tennis’.
Former world No 1 Roger Federer wrote: “Epic start to the year by @DjokerNole. Epic end to the year by @andy_murray, ending #1 Congrats guys”.