A lacklustre Rovers side were beaten by two goals from Ireland U21 striker, Stephen Elliott, and a penalty from the fit-again Macken.
Macken, returning after a foot injury in his only senior appearance this season in Cardiff, combined well with the Irish striker until his departure on 64 minutes.
But it was Elliott who scored the opener after 9 minutes after Jamie Tandy’s ball into the box. Elliott controlled and turned in one movement before clipping a left-foot effort across goal, inside David Yelldell’s left-hand post.
Elliott, who missed a bagful against Newcastle, continued to threaten the visitors’ goal. The inside of Yelldell’s leg blocked the second when one-on-one with Elliott before the striker had two efforts from distance - one going wide and the other saved.
City’s second came on half-time after Jonathan D’Laryea combined with Elliott to release Macken. The former Preston striker knocked the ball wide of the oncoming keeper and he appeared to get a hand to the ball before bringing Macken down but the penalty was given - the dramatic referee bringing much amusement to the 801 spectators. Macken easily stroked home from the spot.
Macken’s flick on 62 minutes released Elliott once more and this time he made no mistake, firing hard and low with his left to nutmeg Yelldell. Elliott might have had a hat-trick after being played in by sub, Stephen Ireland, in the closing stages but he should still be pleased with his night’s work.
Ireland also had a shot turned round the post and Bradley Wright-Phillips, Macken's replacement, fired wide twice.
Blackburn were uninspired and only had one chance of note in the first half with Jerome Watt firing wide. As City tired, Kevin Ellegaard saved well from Peter Corvino and Jemail Johnson to maintain a clean-sheet.
A versatile performance from Willo Flood at right-back is also worthy of a mention.
City: Ellegaard; Flood, Nathan D'Laryea, McCarthy (Onouha, ht), Jordan (c); Croft, Negouai (Ireland, 78), Jonathan D'Laryea, Tandy; Macken (Wright-Phillips, 64), Elliott.
Unused Subs: Schmeichel, Murphy.