The BBC Symphony Orchestra (BBC SO) is a British orchestra based in London. Founded in 1930, it was the first permanent salaried orchestra in London, and is the only one of the city's five major symphony orchestras not to be self-governing. The BBC SO is the principal orchestra of the British Broadcasting Corporation (BBC).

The orchestra was originally conceived in 1928 as a joint enterprise by the BBC and the conductor Sir Thomas Beecham, but the latter withdrew the next year; and the task of assembling and training the orchestra fell to the BBC's director of music, Adrian Boult. Among its guest conductors in its first years was Arturo Toscanini, who judged it the finest orchestra he had ever conducted. During and after the Second World War, Boult strove to maintain standards, but the senior management of the post-war BBC did not allocate the orchestra the resources to meet competition from new and well-funded rivals.