The 56-year-old, who shot to prominence when he was cast in 1991 musical comedy film The Commitments, was long-time frontman of acclaimed rock band The Frames.
Tributes have been paid across world of music from the likes of Ed Sheeran and Bruce Springsteen, who said he was "heartbroken".
Hansard had a storied career in music across more than three decades, including winning the Academy Award for Best Original Song in 2008 with Marketa Irglova, which featured in the low-budget musical romance film Once.
He and Irglova released three albums as The Swell Season, while Hansard also encountered success as a solo artist with 2016 album Didn't He Ramble being nominated for a Grammy in 2016.
The single-vehicle crash happened on Lower Road in Lucan, west of Dublin, and was reported to emergency services shortly before 04:30 local time.
In a statement, ATC Management who represented the musician, said his family was "deeply shocked and heartbroken".
"The family is grateful for the support they have received and wishes to thank the emergency services who attended the scene."
Hansard, the father of a three-year-old boy, has also been hailed by charities for his work in raising money for the homeless.
2010, he started an annual Christmas Eve busk in Dublin City Centre, which attracted high-profile musicians including Bono, Sinéad O'Connor and Shane McGowan.
The Simon Community, a charity in the UK and Ireland which helps homeless people, said it was "devastated" by his death.
"Glen's talents will indeed be his legacy but so too will his commitment to social justice. We will be forever indebted to him for the difference he made in the lives of the people we serve."
