The Trinidad and Tobago international had gone almost two years without a goal before McCarthy took charge at Portman Road, but has since fired the Blues to wins against Bolton and Derby before finding the scoresheet for the third time in eight games in the 3-1 victory against Birmingham on Saturday.
That result ensured McCarthy's men would be a Championship side again next season and Edwards has thanked the former Republic of Ireland boss for the turnaround in the club's fortunes.
He told the East Anglian Daily Times: "Words cannot explain how beneficial he 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.
"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.
"When they have belief in you, it gives you a bigger incentive."