Carter - nicknamed 'The Captain' because he possesses a pilot's licence - continues to battle bad health in the form of Crohn's Disease while he almost faced bad luck before this tournament began after his cue was lost in transit from the UK, apparently turning up around an hour before his opening match at Berlin's Tempodrom.
"The captain landed it tonight," said Carter as he posed with the trophy and a cheque for 60,000 euros. "It was tough out there tonight. Marco struggled a bit. We were both keen to put on a good show for the crowd, and I'm delighted to come out the winner at the end of the week.
"Things have turned around for me massively. I just give it my all..it is very satisfying to come out the winner here."
This was Carter's third ranking event success and probably his biggest coming after winning the Welsh Open in 2009 and the Shanghai Masters a year later.
He is probably most renowned for losing the World Championship final twice to Ronnie O'Sullivan in 2008 and 2012.
Trailing 5-3 from the afternoon session, Essex potter Carter quickly set out his agenda before a crowd of two thousand observant German snooker fans with breaks of 116 and 121 carrying him level with Fu doing little or nothing wrong.
Fu was obviously mentally winded and passed up several obvious chances as Carter pocketed his third straight frame to lead for the first time at 6-5.
Fu had spent 86 minutes without potting a ball in the opening three frames of the evening, and it began to show in his stuttering play.
The man from Happy Valley in Hong Kong was cutting a dejected figure, but managed to pinch the 12th frame aided by a 48 after Carter had missed a brown with the rest in trying to free the yellow.
Despite that error, there was a feeling that Fu's safety and scoring game was struggling to cope with the occasion.
That theme was played out as Carter collected the final three frames with Fu continuing to fall away, perhaps drained by the tactical nature of his 6-4 win over Barry Hawkins in Saturday's semi-final that ran for over four hours.
A run of 71 carried Carter to the brink at 8-6 before he dominated the final frame of the match with Fu's fate sealed long before Carter sunk the winning balls.
"Ali played very well tonight so all credit to him. I just didn't play very well tonight, and was faced with a lot of tough shots," said Fu. "It is nice to be in the final again. The crowd have been great this week. Hopefully, I can come back next year and win it."
Marco Fu will carry a 5-3 lead into the closing session of the German Masters final against Ali Carter at Berlin's Tempodrom.
The 2007 Grand Prix winner was perhaps fortunate to open up an advantage with Carter missing a cut on a red to present Fu with the chance to sneak the eighth frame when 4-4 seemed a likelier outcome.
Fu edged himself ahead by winning an elongated opening frame of the day that lasted almost one hour. He never fell behind from that point onwards.
Double world championship finalist Carter retrieved the two snookers he needed to give himself a chance to win the first frame, but Fu finally scrambled into the lead by holing a splendid long pink with the tension already palpable before almost two thousand German snooker fans.
A break of 55 earned the man from Happy Valley in Hong Kong a 2-0 lead before Carter won his first frame of the final with his own version of Fu's 55.
Carter was first among the balls in the fourth frame, but paid a heavy price for a glaring miss on a red using the rest as Fu returned to the table to piece together an imperious 104 for a 3-1 advantage.
Carter redoubled his efforts after the mid-session interval to draw level at 3-3.
A 70 was enough to win the fifth frame with Fu slipping up among the balls on 38 as the break concluded messily with what appeared to be a push shot.
Carter worked his way back into the frame with Fu missing a long red late in the frame that would ultimately cost him it.
As both men suddenly warmed to their respective tasks in the vast arena, errors were being punished and Carter would watch Fu make 83 for a 4-3 advantage after an attempt to escape from a snooker left his opponent with plenty of balls to go at.
It seemed likely that it would go 4-4, but Carter somehow missed a cut on a red at the scoring end of the table after Fu had made a mess of potting an easy black off its spot.
Fu's 33 was enough to leave Carter needing a snooker, but this time there would be no late drama in trying to get them.
It might yet prove to be a pivotal moment in the final with the first man to nine frames claiming the trophy and cheque for 60,000 euros when they resume play at 7pm (GMT) this evening.