'BX' was the designation of Allied convoys (together with a numerical suffix) plying the route from St John, New Brunswick, and later Boston, Massachusetts, to Halifax, Nova Scotia, to link with HX convoys, and as such reciprocals of the 'XB' series (March 1942/May 1945).

The first of the 206 such convoys was BX.1 of 21/22 March 1942 with the 4,643-ton Greek Dimitrios Chandris, 4,312-ton Belgian Hainaut, 2,254-ton Danish Lifland and 4,062-ton Yugoslav Lucijana. The last was BX.164 of 22/24 May 1945 with 22 merchant vessels and three escorts.