The Melbourne cueist took the last 4 frames in a row, – after O’Sullivan compiled the highest break of the tournament – 143 – to win the match 6-3.
Robertson who last won a tournament in Riga at the start of last season, came into this, completely out of form.
The non-ranking event featured world champion, Mark Selby, who was competing for the first time this season, after breaking his toe. He lost to Robertson in the semi-final.
O’Sullivan beat John Higgins and Judd Trump in the quarter and semi-final matches.
With the season underway, which has already see China win the World Cup, the next world ranking tournament is the new China Championship. This was won as an invitational last season by John Higgins.
The first tournament of the 2017/2018 was won by Ryan Day who is the Riga Masters champion. The opening tournament of the season, see the Welshman claim his first world ranking tournament victory on the circuit in his career, by beating Stephen Maguire in the final.