The 18-year-old signed his first pro deal last year and broke into the team in April, going on win the Wehrlys Bros Player of the Month in April and May and producing magnficient display at the heart of the defence.
A produce of the club’s underage system and Ballisodare United, Mahon has penned the deal to the end of 2020.
Mahon said: “I’m delighted. When I finished my exams last year, all I wanted was to make a career in football. I was given a chance in April and I’ve taken it I think.
“There is massive competition among our centre halves but I want to start every week. I think the gaffer said last week that I was the first name on the teamsheet recently and that’s how I want it to stay.
“I want to do the best I can for the club. It means a lot to me to play for my local club and play in the league. The step up from Under-19 is that it’s much quicker and sharper but I can handle the physicality. In training I work hard to get better and keep improving. I know I’m young but I want to keep progressing and progressing.
“I want to test myself against the best players and I feel I’ve done well so far. But there is a more ahead. Our target is to the get the club up the table and be back in contention for the top half positions.
“I’m grateful to my coaches, from growing up to the underage here and now the gaffer. The gaffer has treated me well, I want to do well for him as well. He has built a relationship with my family too so they know he has the best intentions for me.
“Over the period of this contract I want to get better and better and help Sligo Rovers become one of the best teams in this league. I’ll give it my all.”
Gerard Lyttle said: “John has a massive future in the game. It’s there for him to go on to bigger things. He can be a real proper centre-half.
“It shows big intentions too I think. The players in our academy teams sees the club will invest in them. We’ve sees it from Regan Donelon and Gary Boylan to now John and Jack Keaney.
“It’s a credit to all the underage coaches for the time and effort put in. They’ve helped produce what we’ve seen in the last two months; a really outstanding defender and a huge prospect.
“He has a will to win, he is one of our own and he has all the attributes. The way he has slotted in seamlessly and been our best player in many watches has been a joy to watch. I speak with his Mum and Dad and he has a great support around him, guiding him and that’s important. I’m glad to do that just so when they need to know when there are ups and downs. There’ll be ups and downs like for any player and we have to keep in mind that he is just 18. I see John having a massive future ahead of him and the club has shown that faith in him today.
“I think he’ll take this chance and go on to get better and better and it’s really great for our supporters to watch a Sligo lad with that ability. We’re excited and pleased with getting this done today.”