Michael John Kells Fleetwood was born in Redruth, second child to John Joseph Kells Fleetwood and Bridget Maureen (nee Brereton) Fleetwood. His elder sister Susan Fleetwood, who died of cancer in 1995, became an actress. In early childhood Fleetwood and his family followed his father, a Royal Air Force fighter pilot, to Egypt. After about six years, they moved to Norway where his father was posted on a NATO deployment.

In November 1977 Fleetwood and Nicks began having an affair. It would continue sporadically for the next two years during the fallout from the end of Fleetwood's relationship with Boyd, until the pair mutually decided to end the affair. "Never in a million years could you have told me that [her affair with Fleetwood] would happen," Nicks later stated. "Everybody was angry, because Mick was married to a wonderful girl and had two wonderful children. I was horrified. I loved these people. I loved his family. So it couldn't possibly work out. And it didn't. I just couldn't." Boyd and Fleetwood had in fact begun living together once more in 1976, and would remarry temporarily to assist their children with emigration to the United States. However they quickly divorced for the second time some months later. In November 1978 Fleetwood moved into a Bel Air home with Sara Recor, mutual friend of Fleetwood and Nicks who was at the time married to another music producer. Meanwhile, Fleetwood began working on a charity project to get Fleetwood Mac to tour the Soviet Union, however the Soviet War in Afghanistan later made the tour untenable.  Tusk, Fleetwood Mac's 12th studio album, was released in 1979. The work represented a more experimental direction taken by Buckingham. Fleetwood, recently diagnosed as having diabetes after suffering recurring bouts of hypoglycemia during several live shows, was again instrumental in maintaining the band's cohesion. He placated Buckingham over feelings of creative claustrophobia and discomfort playing alongside Nicks. On the issue of Buckingham taking creative control away from the other members of the group for the creation of Tusk, Fleetwood recounts that his three-day discussion with Buckingham culminated in him telling the latter that "if it's good, then go ahead." Though the nature of the album strained relationships again within the band - particularly John McVie, a long-established blues musician who disliked the experimental nature of the album - Fleetwood himself rates the album as his favourite by Fleetwood Mac, and cites the freedom of creative expression allotted to each band member as integral to the survival of the group. The album sold four million copies worldwide, a return noticeably poorer than Rumours. Though Buckingham was blamed by the record labels, Fleetwood linked the album's relative failure to the RKO radio chain playing the album in its entirety prior to release, thus allowing mass home taping.  Later that year, Fleetwood Mac embarked on a lengthy tour that brought them across America, Canada, Australia, New Zealand, Japan, France, Germany, Switzerland, Belgium, the Netherlands, and the UK. The tour lasted from October 1979 to September 1980, consisting of 113 concerts.

Did Fleetwood Mac experiment with any other albums?
Later that year, Fleetwood Mac embarked on a lengthy tour