The Swedish composer will work closely with the orchestra for one year, culminating in a specially commissioned work.
Andersson will conduct the orchestra in a series of his own works, as well as pieces by fellow Swedish composers.
Thomas Søndergård, principal conductor of BBC NOW, said: ‘It’s with great pleasure that I’m able to introduce B Tommy Andersson to BBC NOW and our audiences in Wales. B Tommy and I have known each other and worked together for many years, and I know that the orchestra really enjoys his music, which is full of such striking ideas.’
Andersson will also work closely with a new generation of Welsh composers in the Composition: Wales project.
Previous composers who have held the role include Michael Berkeley and Simon Holt.