Radcliffe paid tribute to his co-star, who he hailed as a "wonderful man" and "outstanding actor". Gambon starred as the much loved Professor Albus Dumbledore in six Harry Potter films, including Harry Potter And The Prisoner of Azkaban through to Harry Potter And The Deathly Hallows: Part 2.
Gambon took over the role from Richard Harris, who passed away in 2002.
Paying tribute to Gambon, Radcliffe said, "With the loss of Michael Gambon the world just became considerably less fun".
"Michael Gambon was one of the most brilliant, effortless actors I’ve ever had the privilege of working with, but despite his immense talent, the thing I will remember most about him is how much fun he had doing his job. He was silly, irreverent and hilarious. He loved his job, but never seemed defined by it", the actor continued.
Radcliffe who starred as Harry Potter in the films, also lauded Gambon as an "incredible story and joke teller", who made their time on set "more memorable and joyous than they had any right to be".
"I’m so sad to hear he has passed, but I am so grateful for the fact that I am one of the lucky people who got to work with him".
Co stars of the films Rupert Grint and Emma Watson who played Ron Weasley and Hermione Granger, also paid homage to Michael Gambon.
While he did not take things "too seriously", Watson said that Gambon still delivered, "the most serious moments with all the gravitas".
"Thank you for showing us what it looks like to wear greatness lightly. We will miss you xx", she added.
Other actors who featured in the films also include Jason Isaacs (Lucius Malfoy), and Fiona Shaw (Petunia Dursley).
"He took over from Richard Harris and of course, he began to mimic Richard Harris, who had recently died, and he would do his accent, the slight Irish accent", Shaw said. "Which of course he always loved having an excuse to do because his family had come from Ireland, and gone to live in Camden. He just loved the precariousness of reality and unreality and, of course, that made him a very great actor".
Isaacs added that Gambon "shared his fearless, filthy sense of fun" with him, while James Phelps who played Fred Weasley hailed Gambon as a "legend" on and off camera.
JK Rowling who wrote the Harry Potter books, which the films were based on, said that Gambon "would appear in anything I'd written, I’d have thought you were insane".
Rowling first saw Gambon act in King Lear in 1982. She recalled her experience of working with Gambon on the Harry Potter films, and the BBC's 2015 adaption of her book, 'The Casual Vacancy'.
"Michael was a wonderful man in addition to being an outstanding actor, and I absolutely loved working with him, not only on Potter but also The Casual Vacancy", she said.
