He has been on screen for 37 years, but he has never uttered a word. Now, Gromit will speak for the first time – with the voice of the Hobbit star Martin Freeman.

The claymation dog, who has partnered with his eccentric inventor-owner Wallace in a series of Oscar-winning films including The Wrong Trousers, A Close Shave and Wallace & Gromit: The Curse of the Were-Rabbit, is releasing an autobiography this month – including an audiobook edition.

"When you create a character who has no voice and whose facial expressions are everything, what do you do when your publisher reminds you there'll be an audiobook?" said Nick Park, the animator and film-maker who created the series. "Who could possibly be the voice of a character everyone feels they know, but nobody's actually heard?

"The more I thought about it, the more I realised Martin Freeman was the obvious choice, really. I was genuinely thrilled and honoured when he said yes."

Freeman previously honed the role of put-upon sidekick in his Bafta- and Emmy-winning turn as Dr John Watson to Benedict Cumberbatch's unpredictable detective in Sherlock. It should stand him in good stead to voice Gromit – who has had to put up with Wallace variously falling in love with a serial killer, welcoming in a hardened criminal penguin as a lodger, and inventing a hackable robot gnome that spawned an army of evil garden decorations.

Freeman won't be taking too much creative licence with the character, however. "Martin is not doing a Gromit 'voice' as such," said Park. "He's reading Gromit's story as Gromit put it: his inner thoughts, his candid insights and endless witticisms, bringing to them his usual colour, thoughtfulness and wry humour."

The book is not the only spin-off of the franchise in the works. Larger Than Life, an immersive, behind-the-scenes experience projected across four 11-metre walls, will open on 14 October at the Lightroom in King's Cross, London.

Grand: The Autobiography of Gromit, as told to Nick Park, will be published on 22 October.