In 1959, Börje Jansson won the Swedish Junior Chess Championship.

Börje Jansson participated in the finals of the Swedish Chess Championship many times and won eight medals: 2 gold (1968, 1970), 3 silver (1967, 1969, 1977) and 2 bronze (1965, 1972).

In 1969, in Raach am Hochgebirge, he participated in a World Chess Championship Zonal tournament and ranked 10th.

Börje Jansson shared first place three times in the international chess tournaments Rilton Cup in Stockholm: 1973/74, 1975/76 and 1977/78.

In 2004, Börje Jansson won the Swedish Senior Chess Championship in the S60 age group.