"Although the couple have separated, they remain great friends and are committed to jointly raising their two daughters," a rep told People.com.
Michaels, 49, and Gibson, 41, are parents to Raine Elizabeth, 12, and Jorja Bleu, 7.
The “Every Rose Has Its Thorns” singer finally proposed to Gibson in 2010 on the finale of his VH1 show “Bret Michaels: Life As I Know It.”
Gibson had also been with Michaels through a series of life-threatening illnesses, including an emergency appendectomy, a near-fatal brain hemorrhage and a stroke.
Rocker Bret Michaels has found a thorn in his rose. He and longtime girlfriend Kristi Gibson have pulled the plug on their 16-year relationship.