Raine joined W Communications as an associate director in 2014 and has been deputy MD for the past three years.
Ketchum director Alicia Solanki has been promoted to consumer brand deputy MD.
Raine announced she was leaving W in a LinkedIn post.
She said: “When I started at W, I was an associate director, the 24th member of staff and single. I leave the agency as deputy MD, with over 100 employees and as a mother of two," she said.
“I feel privileged to have worked with so many talented people and have made memories and friendships that will last a lifetime.
“I’m moving into a very exciting role, which I can’t wait to share very soon.”
W Communications CEO and founder Warren Johnson said: "We wish her luck in her new role when she starts back from maternity leave later in the year."