Grounded in the Celtic musical traditions, Rennie takes the listener on a journey through history, weaving together tunes and songs and the tales that accompany them to create an intricate and varied show. His engaging stage presence and storytelling opens the door for audiences to connect with the music, which he plays on the wooden flute, guitar, Irish tin whistles, bodhran, fiddle and voice.

Rennie grew up in Wellington with Celtic music in his blood. Having heard the traditional music of Ireland and Scotland on his parents CDs as a baby, he grew up knowing he just had to learn to play like this. He picked up the flute at age 8, learning by ear in Irish sessions under the guidance of Galway born flute player Pat Higgins. With Irish music as the cornerstone of his knowledge, he then went on to delve deep into the traditional music of Scotland and Maritime Canada, gaining proficiency in a wide range of different instruments along the way.

Rennie has made a name for himself in the traditional music scene of Australia and New Zealand as a stand-out solo performer, as well as touring his own duos, bands, and performing with large international stage productions. He has played and taught all over The World, including music schools such as Ceol Aneas, ScotsStrings, CelticANZ, Gaeltached, The National Celtic Festival, Boxwood and folk festivals in Auckland, Wellington, Dunedin, Christchurch, Tasmania and Port Fairy. He has worked closely with the New Zealand Irish ambassador, Peter Ryan, on numerous occasions including performing his show at the Dunedin Fringe Festival with the Irish embassy's support and putting together two tours with his five piece Irish band Criú. He has also toured with Irish Dance troupes Celtica, Rhythm Of The Dance and Celtic Illusion in NZ, Australia and China as their flute and bodhran player, performing in large theaters such as the Melbourne Arts Center, the Wellington Opera House, the Christchurch Isaac Theatre and the Bruce Mason Center in Auckland.

In 2020 he released his first album with Oscar West as their kiwi folk duo Polytropos. His Solo album 'From Across the Seas', was released in 2022 and the most recent release 'AIR' came out in 2023. 'AIR' is an acoustic EP of all original tracks for flutes whistles and guitar, recorded with Bob McNeill as their duo 'Half Light'