The 28-year-old singer left the girl group in February 2010 and though she agonised over quitting the band, she always knew it was for the best.
She explained: "It was the hardest decision I ever had to make in my life.
"I was living the dream but I still wasn't super satisfied or happy. I knew I had to change my situation or change myself.
"It became apparent I wasn't going to be able to grow creatively any more. It was hard to figure out who I was after that. The band had been my identity for seven years - it was a lot to let go of. All I could do was listen to my heart."
Kimberley was part of the best known line up of the group, who rose to worldwide prominence with their musical debut single 'Don't Cha' alongside Jessica Sutta, Ashley Roberts, Melody Thornton, Carmit Bachar and Nicole Scherzinger in 2005, and although she describes her former group as a "machine" and "boot camp", she is still proud of her time in the band.
She added to the Daily Mirror newspaper: "It was a machine. I was proud to be a part of it. It was the best bootcamp I ever could have in the music industry ,but as far as creativity, writing and singing was concerned, I just wasn't part of it. The Dolls wasn't really a collaboration."
Kimberley's new group, Her Majesty And The Wolves released their debut single 'Stars In Your Eyes' this week.