Gruffudd lives in Cardiff and works as a freelance writer. He has worked as a scriptwriter on series 'Pobol y Cwm', 'Rownd a Rownd' and 'Stad'. In 2018 he won the Cardiff National Eisteddfod Chair. He was the Children's Poet laureate of Wales from 2019 to 2021.

He is the author of two volumes of poems for adults namely, 'Hel llus yn y glaw’ (Gathering Bilberries in the Rain) (2015) and 'Mymryn Rhyddid’ (A Little Freedom) (2023) which went on to win the Wales Book of the Year poetry category 2024.

Theatr Genedlaethol Cymru toured his play 'Parti Priodas' (A Wedding Party) in Spring 2024 and his next play '1936' will tour with Theatr Bara Caws in November 2024.