City head into the break a goal and a man down after Seaborne showed straight red and Akinfenwa converts penalty
Coventry City head into the break a goal and a man down after Dan Seaborne was handed a straight red card for a foul on Cody McDonald and Adebayo Akinfenwa tucked away the resulting penalty.
City appeared largely comfortable in the opening exchanges but McDonald turned Seaborne after 22 minutes and was then brought down by the centre half who was given his marching orders by referee Darren Sheldrake after he consulted his assistant.
Akinfenwa then stroked home the spot kick to give the Gills a half time advantage.
Sky Blues boss Steven Pressleyt rang two changes to the side that lost 2-1 at Colchester on Saturday, bringing in Nathan Delfouneso and Franck Moussa in plavce of Blair Adams and the absent Chuba Akpom.
City started the game brightly with plenty of energy and urgency and they very nearly went ahead after five minutes when Moussa got to the byline and chipped a delicate cross into the box which nearly crept inside the far post but rested on top of the goal.
Gillingham had a chance of their own on 19 minutes after an opening period of tussles between the two sides when Leon Legge headed over the bar from a corner.
Callum Wilson nearly steered in an opener two minutes later when he stretched to reach a looping ball from John Fleck and tried to lift a finish over Stuart Nelson but also lifted the ball over the bar.
Proceedings took an unwelcome turn for City after 22 minutes though when they found themselves down to ten men. Cody McDonald turned Dan Seaborne in the box but was brought down by the defender with referee Darren Sheldrake pointing to the spot and also giving Seaborne a straight red card after consulting with his assistant.
Akinfenwa then stepped up to take the penalty, sending Joe Murphy the wrong way to give the hosts the lead.
Coventry City: Murphy, Webster, Seaborne (c), Willis, Clarke, Fleck, Thomas, Moussa, Petrasso (Adams 26), Wilson, Delfouneso
Subs: Burge (GK), Christie, Baker, McGeouch, Barton, Marshall
Gillingham: Nelson, Martin, Legge, Akinfenwa, McDonald, Weston, Gregory, Lee, Barrett (c), Hewitt, Hessenthaler
Subs: Baxter (GK), Linganzi, Davies, Dack, Fagan, Borrowdale, Pigott