The Northern Ireland international scored the opening goal in the Tigers 2-1 win at Lincoln City on Saturday as they sealed an immediate return to the Championship with two games to spare.
Magennis, who turns 31 in August, has scored 19 goals for club and country this season and has been in fine form of late, netting six goals in his last six games.
The goals have come at a decisive point of the season for City, who have won five of their last six fixtures to pull away from the chasing pack to earn promotion back to the second tier at the first time of asking.
“He enjoys playing in the system we play. He is a big part of everything we do here,” said McCann.
“Whether that is his hold-up play, his link-up play, his pressing from front – he has been excellent. He is like a fine wine, he seems to be getting better with age.
“If you ask Josh, he will say he will be able to play for the next 15 years with the way he feels at the minute.”
Hull are the top scorers in League One this year with 77 goals.
McCann has praised the impact that Magennis has had on the players around him, with Mallik Wilks scoring 22 goals in all competitions this campaign while Keane Lewis-Potter has 14 strikes to his name.
Magennis has also provided five assists during a fine season and his manager hopes to see him add to his goal tally in the final weeks of the campaign.
McCann added: “He has been phenomenal, not only on the pitch but off it as well.
“He has got young players, the likes of Keane Lewis-Potter, Mallik Wilks and James Scott, those three in particular he has taken under his wing and helped them.
“It is not only his goals, it is setting things up in games or how he controls games with his voice.
“He is a bit of a character but he is a good lad.
“It is good to see him getting amongst the goals, he looks a threat every time he gets onto the pitch.
“I am hoping he continues that in these next two games and maybe adds to the tally.”
Hull will be guaranteed the League One title if they win their final two outings against Wigan Athletic and Charlton Athletic.
Support The Yorkshire Post and become a subscriber today. Your subscription will help us to continue to bring quality news to the people of Yorkshire. In return, you’ll see fewer ads on site, get free access to our app and receive exclusive members-only offers. Click HERE to subscribe.