Katy Perry has signed a $3 million deal to write her autobiography.

The "Firework" hitmaker - who is currently dating John Mayer - is expected to discuss in detail her 14-month marriage to British comic Russell Brand in the tome, which will be called Part of Me because she wants to put out her side of the story before her former spouse releases the next installment of his My Booky Wook autobiographical series.

"Several publishers have been after Katy for a while. She decided to go ahead so fans don't have a one-sided story when Russell publishes another Booky Wook," a source told The Sun.

The news comes weeks after Russell - who has written two books about his life, My Booky Wook and Booky Wook 2: This Time It's Personal - confirmed he was discuss his relationship with the pop star in his third literary offering because he knows he can't ignore something that was such a huge part of his life.

"I will write more Booky Wooks, I love writing those Booky Wooks and there's a lot to cover. Maybe I'll wait until I get married again or have more children before I write any more. You can't write things about your life and not include things that happened in your life," said Russell, who split from Katy in December 2011.