Prior to Super Furry Animals's formation, Gruff played in a number of other bands, including the Creation Records-signed Emily, and Ffa Coffi Pawb.

Eclectic and eccentric, Gruff Rhys has released several solo albums. His debut album [m169930] released in 2005 and recorded entirely in his native Welsh language, followed by [m169929] released in 2007. [m312080], released in 2011, was the winner of the inaugural Welsh Music Prize in 2011. He released [m686027] in 2014. In 2016 he released [m1075794], the original soundtrack to the film with the same name. [m1375981] was released in 2018 and [m1605842] in 2019. [r15836016] was a Record Store Day 2020 release which featured raw recordings, from 2016, of songs which would eventually be released as [m1375981]. 2021 saw the release of [m2134882].

In 2008 Gruff collaborated with Boom Bip and released [m75083], a concept album with a string of guest musicians. The album was based on the rise and fall of John De Lorean, the founder of the De Lorean Motor Company. Their next collaboration, [m551705], was released in 2013. This was also a concept album and based on the life of Italian publisher and leftwing activist Giangiacomo Feltrinelli.

In 2010 Gruff collaborated with Brazilian eccentric Tony da Gatorra to release [r2964877]. In addition to this Gruff has collaborated with a host of other musicians, most notably for vocals for the track 'Just War' on [m194186] and 'Superfast Jellyfish' from [m231219].

In 2018 Gruff travelled to Johannesburg, South Africa with Africa Express and contributed to four tracks on [m1575913] and a further track on [m1620992], both of which were released in 2019.