In June, 1955 Boris Spassky represented the Soviet Union at the World Junior Championship in Antwerp and won the event to become World Junior Champion. Also that year, Spassky took third place with 7 wins, 9 draws, and 3 losses in the USSR championship. He then qualified as a Candidate at the Gothenburg interzonal.

In 1956 he shared first place with Mark Taimanov and Yuri Averbakh in the USSR championship, but lost the playoff to Taimanov.

In 1956 he tied for third place at the Amsterdam Candidates tournament.

In 1959 he took second place in the USSR championship, then tied for first place at an international tournament in Moscow.

In 1960 he tied for first with Bobby Fischer as the Mar del Plata, Argentina International. In the 1960 USSR championship, Spassky's ending against David Bronstein was used in the opening sequence of the James Bond film, "From Russia with Love."

In 1961 he won the USSR championship at Baku with 10 wins, 9 draws, and 1 loss. His sister, Irena, had won the USSR championship in draughts (checkers).

In 1963 he tied for first place at the USSR championship at Leningrad with 5 wins and 14 draws, but lost the playoff to Leonid Stein.

Spassky won at Belgrade 1964 and the 1964 Moscow zonal tournament. He then tied for first place at the 1964 Amsterdam interzonal.

In 1965 Spassky defeated Paul Keres, Efim Geller, and Mikhail Tal to become the next world championship challenger. The Petrosian-Spassky world championship match began in April, 1966 in Moscow and Spassky lost by the narrowest of margins with 3 wins, 17 draws, and 4 losses.

Boris Spassky won the 2nd Piatagorsky Cup in Santa Monica, ahead of Fischer in August, 1966. The Spassky-Fischer game from this event had over 1,000 spectators watching as Spassky won.

In 1967 Spassky took first place at Beverwijk and Sochi.

In 1968 Spassky defeated Geller, Bent Larsen, and Victor Korchnoi to become a challenger once again for the world championship. He also won the chess oscar for 1968, and repeated it for 1969.

In March 1969, Spassky began play with Tigran Petrosian in Moscow and won the world championship with 6 wins, 13 draws, and 4 losses. Spassky received $1,400 for his efforts. He later took first place at San Juan 1969.

Spassky took first place at Leiden 1970 and Amsterdam 1970 (tied with Lev Polugaevsky). In 1971 Spassky became the first Soviet to compete in a Swiss System tournament when he played in the 1971 Canadian Open.

Boris Spassky met Bobby Fischer for the world championship in Reykjavik, Iceland in 1972. Spassky lost his world championship title with 3 wins (one win on forfeit), 11 draws, and 7 losses.

In 1973, Spassky again won the USSR championship with 7 wins, 9 draws, and 1 loss.

As a Candidate in 1974, Spassky defeated Robert Byrne in San Juan, Puerto Rico, but lost to Anatoly Karpov in the semi-finals.

In 1977 he defeated Vlastimil Hort and Lajos Portisch in the Candidates matches, but then lost to Victor Korchnoi in Belgrade.

Spassky tied with Karpov at Bugojno 1978 with 6 wins, 8 draws, and 1 loss.

In 1980 Spassky drew with Portisch in the Candidates match, but lost the tie-break. That year he tied for first at Baden with 6 wins and 9 draws.

In 1983 Spassky won at Linares 1983 with 3 wins and 7 draws.

In 1985 Spassky took second place, behind Korchnoi, at Brussels with 8 wins and 5 draws. Spassky tied for second, behind Zoltan Ribli, at Reggio Emilia 1986-7.

In 1988 he tied with Murrey Chandler at Wellington, New Zealand.

In September, 1992 Boris Spassky began another match with Bobby Fischer in Sveti Stefan, Yugoslavia. After 20 years, Fischer came out of retirement to play a rematch with Spassky. Spassky lost the match with 5 wins, 15 draws, and 10 losses.

In 1994 Boris Spassky lost a match with Judit Polgar in Budapest.

In world championship play, Spassky won 12 games, drew 41, and lost 15. His peak rating has been 2690.