He won the World Junior Chess Championship in 1957, the only person to win that tournament with a perfect score.

[8] Lombardy grew up at 838 Beck Street, Bronx, New York City, in an apartment with his parents and two other families.

[12] When Lombardy was about 10 he went to Lion's Square Den Park to play stronger chess players.

[27] In 1958, he played in the Mar del Plata tournament and went "undefeated in second place",[28] scoring 11/15.

[32] Lombardy finished second in the 1960–61 U.S. Championship behind Bobby Fischer and ahead of Raymond Weinstein in a star-studded field.

[33] With this result, Lombardy qualified to compete in the Interzonal tournament to be held in Stockholm for the right to advance to a match for the world championship.

[36] At the 1961 Zurich Chess Tournament, Lombardy tied for fourth place with Svetozar Gligorić, scoring 6½/11.

[16] In 1969, Lombardy tied for second with Vlastimil Hort, going undefeated at Monte Carlo,[48] scoring 7/11.

[30] Lombardy defeated future world champion Boris Spassky in their individual game.

[67] In 1978 and 1979, Lombardy served as the lead instructor at an "all day", week-long chess camp at Michigan State University.

In 1979 Lombardy equaled his earlier score at Lone Pine, tying for fifth–tenth,[68] and winning an upset against tournament favorite (and then World Number 2 player)[69] Victor Korchnoi.

[76] Lombardy essayed the move in at least nine official tournament games, scoring three wins, two losses, and four draws: Fischer was scheduled to play a match against Spassky for the World Chess Championship 1972.

Although Lombardy was still a priest, he was allowed to take time off from the priesthood to go to Reykjavík, Iceland, to serve as the official second[77][72][78] to Fischer.

[80] On September 16, 2015, the American biographical film Pawn Sacrifice was released, starring Tobey Maguire as Bobby Fischer, Liev Schreiber as Boris Spassky, Lily Rabe as Joan Fischer, and Peter Sarsgaard as Lombardy.

[15][71][82] In March 2016, The New York Times reported that Lombardy was embroiled in an eviction battle against his landlord, allegedly being several thousand dollars behind in rent.

[71] The Archdiocese of New York was made aware of his plight and agreed to house him and provide long-term care even though he had left the priesthood.

[71] Lombardy accepted the offer but soon thereafter he left New York to live with a friend, Ralph Palmieri, in Martinez, California.