O'Sullivan needed just 44 minutes to win the final of the European Tour event and capture his first crown since his World Championship triumph in May.
The Rocket collected the top prize of 25,000 Euros after firing breaks of 92, 69, 61 and 110 against Kent-based world number 57 Greene, who was playing in the final of an event carrying ranking points for the first time.
"For the last two years I've been calm and relaxed and enjoying the game, much more so than I had been for the previous 18 years," said O'Sullivan. "I'm playing more aggressively with confidence in my potting accuracy.
"If there's one thing that's keeping me going it's the chance to beat Stephen Hendry's record of world titles and perhaps he's sleeping a bit less easily now I've got to five.
"It's fantastic that Dragonstars have had this tournament going in Germany for ten years. It's easy to forget people, but when you come back to this tournament you see all the pictures of Paul and it makes you stop and think and remember him. As long as snooker is being played this tournament will keep going."
In the semi-finals, O'Sullivan ended Mark Selby's hopes of winning the event for a third consecutive time, winning 4-2, while Greene edged out Ali Carter 4-3.
The European Tour comprises eight events, with the top 24 on the final Order of Merit to qualify for the Grand Finals next March, to be joined by eight more players from the Asian Tour Order of Merit. The next event is the Ruhr Open in Germany from October 3 to 6.
Results (last 16 onwards)
Stuart Bingham 4-1 David Morris
Ronnie O'Sullivan 4-3 Anthony McGill
Robert Milkins 4-1 Martin Gould
Aditya Mehata 1-4 Mark Selby
Joe Swail 4-2 Jamie Jones
Thanawat Tirapongpaiboon 1-4 Gerard Greene
Ken Doherty 2-4 Michael White
Ali Carter 4-2 Ricky Walden
Bingham 0-4 O'Sullivan
Milkins 2-4 Selby
Swail 1-4 Greene
White 3-4 Carter
O'Sullivan 4-2 Selby
Greene 4-3 Carter
O'Sullivan 4-0 Greene
PICTURES by Sandy Giet
Ball by ball scoring and results from tournaments