Coach Brendan Rodgers introduced the Ghanaian into the game at a time Villa had raised their game needing an equalizer, having gone down 1-2 before the hour mark.
Amartey replaced Midfielder Ricardo Pereira in the 76th minute to help the foxes maintain their 2-1 lead, and did impress, helping to hold up play.
Leicester City moved up to second in the Premier League table with that hard-fought 2-1 victory at Aston Villa.
Brendan Rodgers gave his side one task: take all three points. And they delivered. From the moment the first whistle went, the Foxes pinned Villa back with a high-pressing brand of football.
James Maddison opened the scoring after only 19 minutes with a composed low shot from range that nestled into the corner of the net, the England international punishing Villa who had given him far too much time and space.
Harvey Barnes then added a second less than five minutes later. Emi Martinez could not hold on to a venomous Jamie Vardy shot from inside the box, spilling it into the path of Barnes who reacted quickest to smash the ball into the back of the net.
Aston Villa came out quickly in the second half and grabbed a goal through Bertrand Traore, the forward doing well to get on the end of Matt Targett’s cross and sweeping past Kasper Schmeichel.
Despite Villa’s best efforts they did not look the same without captain Jack Grealish, who was out due to injury.
Leicester now have back-to-back home fixtures with Slavia Prague arriving for their Europa League second leg in midweek before Arsenal visit in the league. Meanwhile, next up for Villa is a trip to Elland Road to face Leeds United.