Scotland's fifth seed Higgins, who beat world champion Ronnie O'Sullivan in the semi-finals, saw off Australia's Robertson 4-1 at the Universiada Hall in Sofia to claim his first ranking title since the Shanghai Masters last September.
It is the former world number one's 41st career win and earns him 2000 ranking points and 25,000 euros in prize money.
Higgins comfortably beat Robertson with top breaks of 60, 73, 118 and 82.
"It's a great start to the season for me, especially beating so many good players in one day," Higgins said. "It gives me a lot of extra confidence.
"I'm playing with a new cue which I had made a few weeks ago. I wasn't sure if I'd like it at first because the chevrons are pointing towards the table rather than towards me as I've been used to in the past.
"But it's obviously working so far."
Robertson had done well just to reach the final, having trailed to fourth seed Barry Hawkins in their semi earlier on Sunday. He has also managed a 142 break in his fourth-round win over Anthony Hamilton.
The next European Tour event is the Rotterdam Open from July 19-21.
Bulgarian Open results
Final:
John Higgins [5] 4 - 1 Neil Robertson [1]
Semi-finals:
Neil Robertson [1] 4 - 3 Barry Hawkins [4]
John Higgins [5] 4 - 2 Ronnie O'Sullivan [11]
Quarter-finals:
John Higgins [5] 4 - 2 Fergal O'Brien [26]
Barry Hawkins [4] 4 - 1 Scott Donaldson [61]
Neil Robertson [1] 4 - 2 Jimmy Robertson [38]
Ronnie O'Sullivan [11] 4 - 0 Mark J Williams [9]
Fourth round:
Fergal O'Brien [26] 4 - 1 Stuart Carrington
Scott Donaldson [61] 4 - 1 Matthew Stevens [8]
Robertson [38] 4 - 2 Anthony McGill [35]
Neil Robertson [1] 4 - 1 Anthony Hamilton [31]
Barry Hawkins [4] 4 - 1 Nigel Bond [34]
Mark J Williams [9] 4 - 1 Sam Baird [54]
Ronnie O'Sullivan [11] 4 - 2 Mark Davis [7]
John Higgins [5] 4 - 0 Shaun Murphy [3]
- Sports & Recreation
- John Higgins
- Neil Robertson
- Barry Hawkins
