Valvo was a graduate of Columbia University. He spent much of his life working with computers and is best known for his job as commentator for the Kasparov versus Deep Blue Matches in 1996 and 1997, but he accomplished many things in a chess career going back to the late 1950s.

Valvo learned the game from his father Frank, who was also a USCF master. Michael made quick progress and in 1964 was a member of the U.S. team that competed in the 11th Student Olympiad in Cracow, Poland, in 1964 along with Bill Lombardy, Raymond Weinstein, Charles Kalme, Bernard Zuckerman and Mitchell Sweig. The Americans finished in fourth place behind the USSR, Czechoslovakia and Hungary.

He quit playing chess in 1969, but came back and earned a FIDE rating of 2530 in the late 1970s after an excellent performance in a NY Futurity. FIDE awarded him the IM title in 1980. By 1976, Valvo had essentially dropped out of tournament chess and his rating was no longer published in the USCF rating lists, until Bill Goichberg and Jose Cuchi invited him to a futurity tournament. Valvo did well and his rating rose to 2440. However, Professor Arpad Elo refused to award Valvo the rating because Elo had never heard of Valvo and suspected that the tournament had been rigged.

This matter was debated at the 1978 FIDE Congress in Buenos Aires and FIDE voted to give Valvo his 2440 rating. Valvo quickly proved that he really was a 2440 strength player and earned the International Master title. Valvo never played in the U.S. Chess Championship, but made his mark in computer chess, which became his primary focus.

At every World Computer Chess Championship from the early 1980s until his death, Valvo was the organizer, moderator, commentator or acted in some official capacity. He also played a two game play by email match against Deep Thought, winning both games.

A respected opening theoretician Valvo played 1.e4 for much of his career before adding the English to his repertoire. He was a life-long fan of the Dragon and a early pioneer (1963) of a Benko-gambit. He tested many of his lines in correspondence chess throughout his career. Valvo was a co-author of a book on the 1990 Kasparov-Karpov match and was the technical editor of Bobby Fischer Teaches Chess along with Raymond Weinstein. He did the game annotations for the 1966/67 US Championship bulletin.

Valvo died of a heart attack.