Forssell was a versatile writer who worked within many genres, including poetry, drama and songwriting.

While in attending the University of Uppsala, he became a cultural reporter for various Swedish newspapers and journals (Utsikt, Bonniers Litterära Magasin, Poesi, Dagens Nyheter and Expressen).

At the same time, he became established as a lyricist for cabaret shows and his own reviews (including Två åsnor (A Pair of Donkeys) which was staged in Gothenburg in 1957).

[2] His collections of poetry won him membership of the Swedish Academy in 1971, while his song lyrics brought him widespread public recognition.

During the 1970s he worked tirelessly as a poet and as a song-contest lyricist, including writing for the 1973 Swedish Eurovision Song Contest entry selection round (Melodifestivalen) and for performer Lill-Babs in 1980.