Their third album, named #3, released in 2012, also topped the charts in Ireland and peaked at number two in the UK.
Three more albums followed, No Sound Without Silence, Freedom Child, and Sunsets & Full Moons, all of which reached number one in the album charts in the UK and Ireland.
They have sold more than 20 million albums worldwide, while their music has featured on a number of popular TV shows, including EastEnders, Made In Chelsea and the US comedy-drama 90210.
‘Such a lovely man’
Paying tribute to Sheehan, fellow Irish rock band Kodaline said in a statement posted to Twitter: “So sorry to hear the passing of Mark Sheehan.
“We had the great fortune of getting to spend time in his company over the years and was always such a lovely man. Deepest condolences to his family and his The Script brothers.”
In a tribute, posted on social media, Irish pop duo Jedward wrote: “Everyone in the Irish music industry and worldwide mourn your loss RIP Mark such a talented musician from The Script one of the most iconic Irish groups of our generation.”
Sheehan was a father-of-three. He spent most of his time in the US with his American wife Rina. The pair were married for more than 20 years.
Sheehan missed nearly a year of gigs in 2021 and early 2022 to be close to his family.
He was due to join up with the band later this year to support US pop star P!nk for her European tour.