"Happy birthday baby. God I miss you," Love said alongside a black and white photo of herself and Cobain holding each other while laying down.
Cobain, the frontman of Nirvana, was found dead in his Seattle home on April 8, 1994 with a 20-gauge shotgun laying on his chest. His death was ruled a suicide.
"Please keep going Courtney for Frances," a suicide note read in reference to the pair's daughter, Frances Bean Cobain, now 25. "For her life will be so much happier without me. I love you. I love you," it continued.
Frances Bean recently celebrated on Instagram two years of sobriety after struggling with drug addiction.