The game was preceded by a minute's silence for Nevin Spence and his brother Graham and father Noel who passed away in a tragic farming accident last Saturday.
The Blues made the quicker start with Tom James making a great break inside the first ten minutes and after Treviso were penalised for offside Rhys Patchell gave his side the lead.
On 15 minutes Dan Fish, also recalled to the starting XV, produced a moment of individual brilliance. The full-back evaded three challenges to touch down under the posts as the Blues asserted their dominance early.
Blues prop Benoit Bourrust was then penalised for coming in at the side and Kris Burton converted to get Treviso on the scoreboard.
Roberts then extended the lead in the 30th minute when he bounced off two tackles and to go under the posts. It was great link-up play between Patchell and Roberts which created the try.
The home side were in complete control, leading 17-3 at the break, and things got worse for Treviso immediately after the interval when Robert Barbieri was sent to the sin-bin and Patchell added another three points.
Roberts then saw his pass intercepted by Giulio Toniolatti but Patchell raced back to deny him the try.
The Blues' defence was tested again when Tobias Botes went for the line five metres out but was held up as the home side held strong.
And when the Italians were restored to their full complement their persistence finally paid off as Barbieri powered over for a deserved score after picking up the ball from back of the scrum and driving for the line.
Burton added another penalty 15 minutes from time to bring Treviso back to within a score but the Blues hit back.
Against the run of play Jason Tovey scored a breakaway try, converted by Patchell, only for Bradley Davies' sin bin to give the visitors an opening.
Barbieri went over for his second of the evening but Burton missed the conversion to leave his side more than a score adrift.
And with time up replacement Campese Ma'afu went over for the Blues' bonus point try to seal their first win since their permanent return to the Cardiff Arms Park.
|Cardiff Blues Score Card|
|Benetton Treviso Score Card|