Production is underway on the live-action and animated picture, which will co-star Madeleine Harris and Samuel Joslin -- and feature the voice of Ben Whishaw as the titular bear.
Grant will play Phoenix Buchanan, "a vain, charming acting legend whose star has fallen somewhat in recent years," while Gleeson will portray Knuckles McGinty, "a notorious safe-cracker and legendary strongman who becomes an unexpected new ally for Paddington."
"The much-anticipated sequel to the worldwide hit family film finds Paddington happily settled with the Brown family in Windsor Gardens, where he has become a popular member of the community, spreading joy and marmalade wherever he goes," a Tuesday press release from Studiocanal notes. "While searching for the perfect present for his beloved Aunt Lucy's hundredth birthday, Paddington spots a unique pop-up book in Mr. Gruber's antique shop, and embarks upon a series of odd jobs to buy it. But when the book is stolen, it's up to Paddington and the Browns to unmask the thief."
"It has been a complete joy to return to the world of Paddington. It was such a delight to see his first big-screen adventure embraced by audiences around the world, and I couldn't be more excited about Hugh and Brendan joining the cast to bring his next outing to life. Together, I hope we can make a film worthy of this most exceptional of bears," director Paul King said in a statement.
"I am thrilled to be back in the warm embrace of Paddington Bear, again under the inspired direction of Paul King. And I'm delighted to welcome Hugh and Brendan to our exceptional cast," added producer David Heyman.