With Novak Djokovic and Jo-Wilfried Tsonga also in his round-robin group at London's O2 Arena, defeat in his opening match would have left the US Open champion with an uphill task to qualify for the semi-finals.
And it did not look good for the Murray when he dropped the opening set but the current world number three finally took a break point at the 11th time of asking early in the second and from there he kept Berdych at arm's length to win 3-6 6-3 6-4.
It was Murray's first match in the UK since the heady days of summer when he banished his Centre Court demons by winning Olympic gold.
He followed that, of course, by ending his long wait for a grand slam title in New York and he was roared onto court under the lights of the vast arena.
The opening singles clash of the tournament was a repeat of the US Open semi-final, which Murray won in extremely windy conditions, but he does not have a particularly good record against big-hitting Berdych and was looking to square their head-to-head at 4-4.
The home favourite, for that is certainly what he is now, began with a statement of intent as he powered away a backhand winner but the chance to break went begging, and it was the same story in the fifth game.
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Murray was then made to pay when Berdych took his chance and the Czech saved his sixth and seventh break points of the set to clinch it when his opponent went long.
Murray played only one match at the eight-man end-of-season tournament last year, losing to David Ferrer before pulling out injured.
This year he sounded determined to put on a good show for the home fans but Berdych had not read the script and Murray was under pressure in the third game of the second set, which would prove to be the turning point.
Three times he saved break point and in the next game he finally made the breakthrough despite Berdych clawing his way back from 0-40 for the second time in the match.
It was Murray's 11th break point, and he made sure he did not waste his hard-won advantage, taking his first set point when Berdych drilled a backhand wide.
The sizeable crowd had been a little subdued but they roared when the Scot brought up two more break points in the third game of the decider, and again when Berdych put a forehand just wide.
Coach Ivan Lendl was back in Murray's box for the first time since the US Open and he would have been pleased with the way his charge had turned things around.
The 25-year-old has developed an unwelcome habit since the US Open of losing matches in which he has held match point, doing so in all three tournaments he has played following his New York triumph.
And he betrayed a few nerves with a double fault on his first chance here but on the second Berdych netted a backhand, leaving Murray to roar with delight as the fans acclaimed their man.