Six minutes later the Hull winger tried his luck again, but failed to his keep his left-footed shot on target. Moments later Wade Elliott went close for the home side.
Aluko gave Hull the lead on 14 minutes when he latched on to Jay Simpson's pass and shot home from close range.
The winger doubled his side's advantage in the 26th minute when released by Simpson again, firing in from 12 yards.
It became 3-0 to Hull on 33 minutes when James Chester headed home Aluko's delivery from close range.
However, five minutes later Ravel Morrison pulled one back for Birmingham with a right-footed shot from around 12 yards out.