As Method Motorsport team owner, it was Chaz Mostert’s first victory in the season also, with his second McLaren coming home in third.
In Round 1 at Phillip Island, Hayman and Flack had to settle for second in both races, however, this time it was the blue and pink McLaren that prevailed.
Second place went the way of the Ford Mustang driven by George Miedecke and Rylan Gray, the duo which dominated Round 1.
Miedecke battled hard against Flack in the opening stint, the two exchanging places on a number of occasions, however the Mustang had the straight-line speed and was ahead when the compulsory pitstops began.
With a longer compulsory pitstop time Gray emerged behind Hayman and could not close the margin down.
Both found themselves behind Tom McLennan at the start of the final stint, however McLennan sharing the sister Method McLaren with Nathan Morcom did not have the speed and finished third overall.
Hayman and Flack won by 3.9s from Gray and Miedecke, with McLennan finishing 5s behind the race winner.
Lachlan Mineeff and Shane Smollen driving a Porsche took a comfortable win in the Pro-Am class and finished fourth overall. BMW driver Tim Leahey finished in fifth ahead of Jake Camilleri, making it four brands in the top five.
Josh Buchan led for much of the race outright, but co-driver Jason Yu dropped down the order late in the race and finished in seventh.
Zoe Woods finished the race in eighth ahead of Love Motorsport’s Bailey Love and Sam Brabham.
Jacob Lawrence in his Randall Racing BMW M4 GT4 rounded out the top 10 and also won the Am class in the process.
Tony Quinn and Jackson Rooney finished in 11th ahead of Vince Gucciardo and Mark Griffith who finished second and third in the Am class respectively.
Ryder Quinn and Steve Jakic were next from Antonio Astuti and Rob Love, Peter Lawrence and Jamie Augustine, with Scott Turner and Rob Rubis rounding out the field. All 17 cars made it to the finish line.
The second and final one-hour long Monochrome GT4 Australia Series race at Shell V-Power Motorsport Park takes place at 12.05pm local time (12.35pm AEST) tomorrow.