The Sligo native died at the age of 90 last week, leaving a legacy which included his time as assistant manager to Jock Stein when the club became the first British team to lift the European Cup in 1967.
Ferguson addressed the congregation at the Church of Christ the King in Glasgow, to pay tribute to "a great man".
He said: "I think it's very difficult for people who are successful to remain humble, it's a touch of greatness.
"Sean always had that greatness. Through his background, his upbringing, his Irishness, that breeds humility and also loyalty, he would never let you down."
Although Ferguson was a player with rival Glasgow side Rangers, he formed a strong friendship with Fallon as he built his career as a coach and a manager.
He praised him for his role as assistant manager to Stein and said he was talented in the position, which required him to "get to the heart of the dressing room".
Among the mourners were other Celtic veterans including Kenny Dalglish and Tommy Gemmell. Current players present at the service included captain Scott Brown, Tony Watt, Adam Matthews and Georgios Samaras.
Fallon leaves behind his wife Myra, five daughters and a son.