Boudewijn Cox was awarded diplomas in guitar, chamber music, harmony and counterpoint from the Lemmens Institute in Leuven, where he pursued advanced studies with Luc Van Hove (composition) and Christian Vereecke (fugue). As a composer he has received various prizes: Hommage à Ohana (the compulsory work for the semi-final of the International Guitar Competition Printemps de la Guitare - 1994 in Walcourt) won him first prize in the composition competition for classical guitar held by BAP SABAM. He won the Prometheus Prize in 1995 with his Octet for woodwind ensemble. Onyx for orchestra was awarded a “highly special commendation” in 1997 in Vienna, at the Vienna Modern Masters 6th International Orchestral Recording Award Competition, and a year later Cox won the Youth and Music Prize for Composition in 1998. He became familiar to a wider audience with his Prelude for piano, which was chosen as the compulsory piece for the semi-finals of the 1999 Queen Elisabeth International Music Competition.
Cox composes almost exclusively on commission. In 2002 the Flemish Radio Orchestra premiered his Tableau in the Cultural Centre in Hasselt, with additional performances in De Bijloke in Ghent, De Spil Cultural Centre in Roeselaere and Theater aan de Parade in 's-Hertogenbosch (Holland). In the same year, Equinox for piano, commissioned by the American pianist Jenny Lin, was performed in De Rode Pomp in Ghent, the Flanders Festival in Mechelen and New York’s Carnegie Hall. Boudewijn Cox teaches at the music academies in Wemmel and Beveren.
In 2012 his pianoconcerto was premierd by the Symfonieorkest Vlaanderen conducted by Jan Latham Koenig. In 2019 he composed a work for soprano, piano and string quartet, called 'NN'.