Mullin is set to become Coleman's third addition of the summer following Chris King and Colin Murdock.
"John knows the club through Paul and he's my type of player, he's very dedicated to his profession, has good attributes and is a good footballer.
"If you combine those things he's the sort of player we want here at the football club."
John Mullin, who is 18 months younger than his brother Paul, revealed he had been pondering a move to Accrington for a while following a conversation with his brother.
"He [Paul] mentioned it to me at the end of last season so it was always a thought in the back of my mind.
"We spoke in the summer and it was case of coming down to train and it's been good.
"We've never actually played together at a club, our careers have always taken different paths.
"It's nice that we've come together, we've both got bald heads so that's a start and hopefully we can get a good understanding."