He is the lead singer, rhythm guitarist, and primary songwriter in the Australian pop rock band Thirsty Merc.

Some of his early musical influences are listed as The Beach Boys, Buddy Holly, Deep Purple, Cream, Jimi Hendrix, Iron Maiden, Stevie Wonder, Donny Hathaway, Prince, Frank Sinatra, Joni Mitchell, Mahavishnu Orchestra, Chick Corea, Keith Jarrett, Oscar Peterson and Claude Debussy.

[citation needed] In 2002, Thistlethwayte formed the rock band Thirsty Merc and was subsequently signed by Warner Music Australia.

[4] In June 2013 he opened for Norwegian one man band, loop pedal artist and soul singer "Bernhoft" around the United States and Canada.

[6] He played a late night set after "Puss in Boots" (an all-female group featuring Norah Jones) at Rockwood Music Hall in New York City in June 2013.

In January 2014, Sun Rai collaborated with jazz drummer Ben Vanderwal at Sound Baker Studios in Perth, Western Australia.

He has also featured as a guest musician with the electronic group Knower, and can be seen performing in the live video clips of their tracks "Overtime", "Time Traveler" as well as "It's All Nothing Until It's Everything".

[11][12] Thistlethwayte co-wrote the song "12 Hours" with The Whitlams' Tim Freedman, album title track "Happy Home" with The Voice runner up Darren Percival (Universal Music Australia), the first single "Goodnight America" (Universal Music Australia) for upcoming female artist 'Sinead Burgess.'

He played piano on two songs for ex-Silverchair drummer Ben Gillies' solo album, was the piano player on the singles "You Won't Let Me", by Karise Eden, "Happy Home", and "In The Blowing Wind" performed by Darren Percival and Sarah De Bono's cover of Duffy's Warwick Avenue for the TV series The Voice.

He played multiple instruments on 5 songs for Brian McFadden's record to be released in late 2012: bass, guitar, drum programming and piano.

Thistlethwayte has taught masterclasses at The Australian Institute of Music, Lismore University, Claremont College and Blacktown Tafe and has been a mentor at Song Summit from 2010 to 2012, a week-long annual songwriting conference hosted by APRA, of which he is an Ambassador.

He attended the 'Bali Songwriting Retreat' in Ubud, Bali, in 2011, along with Bonnie McKee, Delta Goodrem, Nick Jonas and Arnthor Birigisson.