Louis Kayes, from Moodiesburn, North Lanarkshire, called the Glasgow club to tell them he was sorry for being unable to attend Celtic’s 2-0 win over Motherwell last Saturday.
It is understood Louis searched for Celtic’s website on his mother’s phone and hit the call button.
Speaking on BBC Radio Scotland’s Kaye Adams programme on Wednesday, the boy’s mother, Lisa Kayes, 35, said Louis wanted to speak to Celtic manager Brendan Rodgers and his favourite player Scott Brown to apologise and explain his absence.
Ms Kayes added: “He wanted to let both of them know he’d missing it in case they were looking for him.
“He’s possibly the most passionate five-year-old I know in terms of supporting Celtic. He doesn’t like to miss a game.”
The youngster went to his first home match against Inverness on May 24, 2015, when he was four and he told BBC Scotland that he would definitely not be missing Celtic’s Champions League clash with Borussia Monchengladbach on Wednesday.