All three of Edwards's goals this season have been scored since McCarthy took charge, while his performances have also improved.
With that in mind, Edwards has thanked the former Republic of Ireland coach for sticking by him.
"Words cannot explain how beneficial [McCarthy] has been for me. I had the honour of playing for him at Wolves during a short loan spell and he knew what I was capable of when he came here," the East Anglian Daily Times quotes Edwards as saying.
"Maybe I was a bit off the boil when he arrived and I have got to thank the manager for keeping faith in me. Along with Terry Connor, he has been on my case to try and be more positive.
"I wasn't scoring as much in the past and I take full responsibility for my actions and, as a player, you don't need coaches to come in and tell you what you already know. When they have belief in you, it gives you a bigger incentive."
Edwards joined the Tractor Boys in 2009 from Sunderland.