Guido Burgstaller and an own goal from Ryan Haines saw Cardiff though to round 2 of the Capital One CUp.
City had to endure a scare in the final 10 minutes when Shaun Miller pulled one back for Coventry but Cardiff held on to win at Sixfields.
Burgstaller scored in the 4th minute of the game and City played the next 60 - 70 mins as a training excercise. Coventry tried to put some pressure on the Bluebirds late in the game but were undone by Simon Moore's kick out to Mats Daehli. The Norwegian crossed to Kadeem Harris to score under pressure but replays showed the ball came off Coventry defender Haines.
Within two minutes though the hosts, playing 35 miles from Coventry, had pulled one back. Haines crossed for Miller to finish.
Cardiff saw out the tricky final minutes and will now face Port Vale away in round 2.
During the game both sets of supporters held up cards saying 'Let Down' in support of Coventry's ridiculous situation where they play in Northampton but also in support of Cardiff having to endure a totally unwanted and unnecessary rebrand.