Selby adds to his success in snaring the invitational tournament at Wembley Arena in 2008 and 2010 while he also becomes the first man to pick up the UK Championship and the Masters - traditionally two of the more celebrated events in snooker alongside the World Championship - since Mark Williams carried them off a decade ago.
Leicester's Selby joins Cliff Thorburn, Steve Davis, Stephen Hendry, Paul Hunter and Ronnie O'Sullivan as the only men to win three or more Masters.
"You always get great crowds here in London, and it gets you up for it," said Selby. "I struggled yesterday. Neil had been the player of the tournament coming into the final. I knew I had to come into the match and attack to beat a player of Neil's class.
"It was nice to play well for a change, and to do it on the big stage. I'll obviously be giving it my all at the World Championship this year."
Robertson failed in his efforts to emulate Thorburn, Hendry and Hunter in becoming only the fourth man to retain the Masters, but can have few complaints about the outcome of this best-of-19 frame final despite mounting a mini-revival from trailing 8-3 to 8-6.
Selby did not finish his 6-5 semi-final win over Graeme Dott until 12.29am on Sunday morning, but his obvious vibrancy seemed to ambush Robertson's scoring game that had harvested six centuries in reaching the final.
In a week in which he was particularly hot in running in six centuries to reach the final, Australia's 2010 world champion chose the wrong day in which to freeze in a snow-laced London.
Trailing 5-3 from the opening session, Robertson - a 10-6 winner over Shaun Murphy in last year's final - could not seem to inject enough gusto into his play as Selby began on the offensive and never really relented.
Robertson had only enjoyed two wins over Selby in their 10 previous encounters so the omens were perhaps not great despite the form book suggesting otherwise.
A break of 67 saw the man from Leicester move 6-3 ahead after his opponent could only piece together eight at the outset of the frame.
Robertson jawed a tough red down a side cushion late in the 10th frame as Selby compiled 24 to the pink for a 7-3 advantage.
Robertson would not score a point in the 11th frame with a sloppy safety shot seeing Selby roll in a closing 32 for an 8-3 lead.
It was obviously imperative that Robertson managed to pick up the 12th frame for the good of his future health in the contest.
He managed the feat with a timely 74, but his situation remained parlous approaching the death throes of the match.
Robertson's state of mind improved when Selby fluked a red, but could not cash in. A missed red to the centre handed Robertson the chance of an 83 break for an 8-5 lead.
The 14th frame came down to a tense finale on the pink and black. Selby needed both to force a re-spot after Robertson narrowly failed to sink a double.
Selby missed a pink by some distance as Robertson stepped in to slot pink in earning his third straight frame to trail 8-6.
The 15th frame ran for 35 minutes. Selby could muster only 22, but was always the likelier figure.
A well executed pot on a long red to a baulk pocket followed by black paved the way for him to win the frame as Robertson failed to recover the snookers he required on the colours.
The end came when Robertson missed a red into a baulk pocket moments after returning from a comfort break.
Both men squandered chances, but Selby left Robertson needing a snooker by slotting a red via a cushion before potting the pink.
It was officially all over with a few more pots seconds later.
"Tonight Mark punished me and he was a really deserving winner," Robertson said. "I thought when I got back to 8-6, I had a chance. But it was always going to be difficult when it went to 9-6 and he finished it off like a champion."
First session report
Mark Selby showed no signs of fatigue from his elongated 6-5 semi-final win over Graeme Dott in opening up a 5-3 lead over defending champion Neil Robertson in the Masters final at Alexandra Palace.
The world number one finished off his match with Dott at 12.29am on Sunday morning, but his play was certainly not tired for large swathes of the afternoon session at the invitational tournament, an event contested by the top 16 players in the world.
Leicester's Selby appeared as fresh as the heavy snow falling outside the London venue in dominating the opening three frames.
Robertson missed a few balls that he had been potting all week, but appeared slightly unsettled as Selby meandered around the table with some purpose in running in 73 in the second frame and a 102 - his first century of the tournament - in the third to establish a 3-0 advantage.
Robertson halted the bleeding with a 78 in the third frame after winning one of those safety exchanges that he had been so keen to avoid before the final began.
He was first at the table in the fifth frame, but missing a black after slotting a long red proved a fatal error with Selby making 84 for a 4-1 lead.
The Australian continued to struggle in the sixth frame as he missed a straight blue on 45 to a centre pocket that barely seemed believable.
Selby engineered a path back into the frame before emerging successful on the colours for a 5-1 advantage.
With two frames left of the session, Robertson was staring a hefty deficit in the face before the evening play.
But it was Selby's turn to slip up in the seventh frame as a blue failed to drop to a centre pocket.
Robertson responded with 63 which was enough for his second frame of the day. Despite missing a red to a centre bag, Selby could not respond.
The 2010 world champion continued his forward momentum after Selby failed to slot another straightforward looking red in the eighth frame. Robertson pieced together 72 to leave himself only two frames adrift before they play to a finish from 8pm this evening.
Selby is chasing a third Masters title while Robertson is bidding to become only the fourth man to successfully defend the title. Cliff Thorburn, Stephen Hendry and Paul Hunter are the only players to retain the trophy
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