After completing a degree in Journalism and Media Communications, Cecelia wrote her first novel at 21 years old. Her debut novel, PS I Love You was published in January 2004, and was followed by Where Rainbows End (aka Love, Rosie) in November 2004. Both novels were adapted to films; PS I Love You starred Hilary Swank and Gerard Butler, and Love, Rosie starred Lily Collins and Sam Claflin.

Cecelia has published a novel every year since then and to date has published 17 novels; PS I Love You, Where Rainbows End, If You Could See Me Now, A Place Called Here, Thanks for the Memories, The Gift, The Book of Tomorrow, The Time of My Life, One Hundred Names, How To Fall in Love, The Year I Met You, The Marble Collector, Flawed, Perfect, Lyrebird, ROAR and Postscript.

To date, Cecelia’s books have sold 25 million copies internationally, are published in over 40 countries, in 30 languages.

Along with writing novels, Cecelia has co-created the US ABC Comedy Samantha Who? and has created many other original TV projects.

Cecelia's latest release, Roar is now in development by Nicole Kidman and Per Saari’s Blossom Films, Bruna Papandrea’s Made Up Stories and Theresa Park’s Per Capita Productions, along with Ahern’s own Greenlight Go Productions label.

Cecelia's next book is the sequel to international best-seller PS I Love You, titled Postscript. Postscript was published in hardback, trade paperback, eBook and audio by HarperCollins on 19th September 2019 in the UK and Ireland. Grand Central Publishing will publish Postscript in February 2020.

Cecelia Ahern is represented by Theresa Park at Park & Fine Literary and Media in New York, and Howie Sanders at Anonymous Content for TV and film.

"The thread that links my work is in capturing that transitional period in people’s lives. I’m drawn to writing about loss, to characters that have fallen and who feel powerless in their lives. I am fascinated and inspired by the human spirit, by the fact that no matter how hopeless we feel and how dark life can be, we do have the courage, strength and bravery to push through our challenging moments. We are the greatest warriors in our own stories. I like to catch my characters as they fall, and bring them from low to high. My characters push through and as a result evolve, become stronger and better equipped for the next challenge that life brings. I like to mix dark with light, sadness with humour, always keeping a balance, and always bringing the story to a place of hope.”