The home side went three goals up in the second half scored by Chang-Hoon Kwon, Jung-Jin Seo and Ki-Hun Yeom, while Roar got a consolation goal thanks to Luke DeVere in the 80th minute.
The first half was tight with few scoring chances, the homeside were content to defend against Roar and to try and catch them on the break.
The first-half ended 0-0 in what was a fair reflection.
The second half was a completely different affair with goals galore.
Suwon opened the scoring six minutes into the half when a Corey Brown pass was intercepted by Jong Tae-Se, who fed the ball to Kwon.
Kwon ran into the area getting past a defender to slot the ball into the goal past Jamie Young to make the score 1-0.
A minute later Roar should have equalised when Brandon Borrello shot wide after running on to Andrija Kaluderovic's knockdown.
The Korean's went 2-0 up in the 61st minute when Jin Seo scored with a shot past Young at the far post after receiving a decent pass from Lee Sang-Ho.
In the 67th minute Ki-hun scored with a brilliant curling free-kick leaving Young with no chance.
Roar pulled a goal back in the 80th minute thanks to DeVere's header from Thomas Broich's perfect free-kick to make the score 3-1.
The visitors did press hard late in the game but it was a bit too late as Suwon held out for the win.
The result sees Beijing Guoan on top of Group G with 10 points followed by Suwon on seven points. Roar are third with four points followed by Urawa Red Diamonds on one point.