Millin died Tuesday, The Daily Telegraph reported. The cause of death was not reported.
During World War II, Millin served as piper to Simon Fraser, the commando officer Lord Lovat, chief of Clan Fraser, who believed the War Office ban on personal pipers did not apply to him, the newspaper said.
During the Normandy invasion, Millin began playing soon after his landing craft left the Solent. Cheers came from other vessels when his music was broadcast over a PA system.
Millin played traditional airs as soldiers fell. German prisoners later told him he was not shot because they thought he was crazy.
"I shall never forget hearing the skirl of Bill Millin's pipes," a soldier, Tom Duncan, told an interviewer. "It is hard to describe the impact it had."
After the war, Millin toured for several years with a theatrical troupe and then trained as a nurse. A native of Glasgow, he moved to Devon in the 1960s.
In 1995, he played the pipes at Lovat's funeral.
Millin was depicted in the movie "The Longest Day." A statue is to be erected next year on Sword Beach.