Australia's Robertson completed a 10-6 success against Murphy in last year's final and was on hand to punish numerous errors by his opponent in compiling two centuries to secure a meeting with Mark Selby or Graeme Dott in Sunday's final.
Murphy threw away at least two frames that may have altered the outcome of proceedings - his highest break of the match was only 48 - but that should not detract from Robertson's standing as the outstanding player at this week's 16-man invitational event.
He has plundered six centuries so far, a third of the tournament's total haul of 18.
Only Cliff Thorburn (1985, 86), Stephen Hendry (1989-93) and Paul Hunter (2001, 02) - who tragically died of cancer at the age of 27 in 2006 - have retained the title.
2010 world champion Robertson will start as a warm favourite to add his name to that list of former holders.
"I feel fantastic to have the chance to defend my title," said Robertson. "It is a real privilege to make back-to-back finals. I've been scoring really heavily this week and pouncing on mistakes by my opponents.
"That is perhaps putting pressure on my opponents.
"There is a lot of work to do in the final. It is going to be a long day, and a tough match either way. Whoever I play, I don't want to be getting involved in too much nonsense (safety exchanges) in the final.
"I won't be playing tomorrow thinking of making history, but it would be great to join that group of players. I wasn't playing when Stephen was dominating and winning his titles, but I remember Paul's wins. He created a lot more interest in the sport and was a great character. He was so good under pressure..and clearing up under pressure."
Robertson hopes making his own unique piece of history will earn plaudits back home especially with home hope Bernard Tomic losing to Roger Federer in the fourth round of the Australian Open tennis tournament.
"There has be no reaction in Australia. not at all," confessed Robertson. "If I win, I'll be in the papers, but if I lose there won't be a word on it.
"It frustrates me a little bit, but what can you do? It is hard because the time difference is key back home.
"The Australian Open tennis is on at the moment. I think Tomic is out so that may give me a little window of opportunity. If I win tomorrow with nine centuries in a row, I might make a little bit of coverage. I'm not home often enough to get the sport up and running really.
"When I do an interview with radio, they still ask about Eddie (Charlton, Australia's world championship finalist from the 1970s) and stuff."
Murphy appeared in the arena sporting a pink shirt, but it was Robertson who was in the pink after Murphy missed a pink in the opening frame. Robertson would run in 84 for a 1-0 lead.
Murphy levelled at 1-1 boosted by a 48 in the second frame after Robertson made a blunder in failing to pot a pink to a centre pocket when he seemed poised to score heavily.
The Melbournian continued where he left off from making three centuries in his win over Mark Allen in the last eight as he pieced together an immaculate 132 for a 2-1 lead.
The real turning point of the match appeared to arrive in the fourth frame as Robertson recovered from needing a snooker to pinch it.
Murphy made 45 early in the frame before returning to the table to hole a red and brown that left his opponent 72-4 behind.
One more red would have won it for Murphy, but he unforgivably missed a simple ball that would have earned him the frame.
Robertson fought back and with Murphy failing to escape from a couple of snookers, Robertson cleared to the black for a 3-1 lead.
Murphy gathered his thoughts after losing such a close frame and managed to scramble over the line in the fifth frame despite breaking down on 41 by missing a black.
A series of errors using the rest was noticeable in Murphy's game and it cost him a certain chance to level at 3-3 when he missed a red on 43 with the balls at his mercy.
Robertson was out of his chair like a dingo on the prowl as he cleared up with 85 to move 4-2 ahead.
His progress towards the final was only held up by a re-rack in the seventh frame as Murphy was forced to sit and watch Robertson knock in a 132 to leave himself one frame short of the final.
Robertson trailed again in the eight frame, but he would recover to win the frame and match in keeping with the theme of the afternoon as another astonishing Murphy miss on a yellow proved to be his final shot of the tournament.
Robertson cleared the colours to finish off the match in his favour with Murphy looking mentally spent.
"That is what happens when you don't take your chances against arguably the best player in the world," said Murphy.
"He and Mark Selby are playing the game the way they want to play it. That is why they are doing so well at the moment. If you are just not quite on your game, you get beaten.
"I wasn't tired at the end, just frustrated. I couldn't control the white ball and make it go where I wanted it to go.
"It was affecting my potting, my break-building and my safety play.
"It made me look a bit silly really. I don't any take positives from today."