Tork's death was announced on his official Facebook page on Thursday.
"It is with beyond-heavy and broken hearts that we share the devastating news that our friend, mentor, teacher, and amazing soul, Peter Tork, has passed from this world," the post read. "As we have mentioned in the past, the PTFB team is made up of Peter's friends, family and colleagues -- we ask for your kindness and understanding in allowing us to grieve this huge loss privately."
"We want to thank each and every one of you for your love, dedication and support of our 'boss.' Having you in our world has meant so very much to all of us. Please know that Peter was extremely appreciative of you, his Torkees, and one of his deepest joys was to be out in front of you, playing his music, and seeing you enjoy what he had to share. We send blessings and thoughts of comfort to you all, with much gratitude," the post read.
Tork was also known as the jokester on the band's popular 1960s TV series.
A cause of death has not been revealed.
The Monkees, which also included band members Michael Nesmith, Micky Dolenz and Davy Jones, are known for their hits like "Daydream Believer" and "I'm a Believer."
The band tweeted a video of Tork with the caption, "@TorkTweet has passed peacefully at the age of 77. We'll be remembering him throughout the day" and asked fans to share their favorite memories.