Murray was in fine form as he opened the annual end-of-season event, featuring the world's top eight players, with the kind of dominant display that hinted the British number one is capable of providing a home winner for the fans.
Söderling, seeded fourth, has had an impressive year, but fifth seed Murray was at his imperious best as he dismissed him in one hour and 20 minutes.
"Tactically it was a great match," Murray said. "I played very smart tennis and even when it was getting tough in the second set and I was on the defensive quite a lot, I stuck to my tactics and managed to come through.
"Robin is a great player. Most of his tournament wins have come indoors. So to win with that score line is obviously great."
Söderling added: "I didn't start off very well. The first set was not very good. I wasn't really there.
"The second set was better and I felt I had him on the run a lot of times. But every time I came in at the net, he came up with a really good shot. So he was just too good."
Murray had the perfect motivation against Soderling as the Swede had replaced him as the world number four after winning the Paris Masters last weekend.
Murray's slump out of the top four after almost two years in that elite group was the result of an inconsistent season which raised fresh doubts about his ability to end his long wait to win a Grand Slam.
The 23-year-old, who lost the Australian Open final to Roger Federer in January, arrived at the Finals in search of a morale-boosting end to the season and made the ideal start to his Group B campaign.
Murray has always thrived on the support he gets a short distance across south London at Wimbledon and playing in front of 20,000 partisan fans was clearly just the tonic he needed.
A brilliant cross-court winner on the run opened up a 30-0 lead in Söderling's second service game and allowed Murray the chance to earn three break points.
He converted the third with a fine return that flashed back past the Swede for the first break.
Söderling's position at four in the world rankings is a career-best mark, but Murray can regain that position from him with a good run here and he refused to offer the Swede a route back into the match.
He broke again for a 5-2 lead after a pair of searing returns proved too hot for Soderling to handle.
With Murray's serve in a smooth groove, there was never any doubt he would close out the set and he did exactly that with a perfectly executed drop shot on his second set point.
Murray admitted he was terrified when British Prime Minister David Cameron asked him to play tennis in his expensively furnished dining room during a visit by the eight finalists to 10 Downing Street this week.
He was much more at home on a more traditional court.
Söderling made the semi-finals here 12 months ago, but the indoor surface seems slower this year and that suited Murray better.
Murray had the answer to everything Söderling threw at him. One swatted winner on the run bringing a huge ovation from the crowd, while he dodged a break point in the sixth game with an ace.
Söderling self-destructed after that as a careless service game, including a double-fault on break-point, allowed Murray to take a 4-3 lead, which he quickly turned into a match-winning advantage.