In 2018, he portrayed Simon Zealotes in the NBC live television concert production of Andrew Lloyd Webber and Tim Rice's Jesus Christ Superstar, for which he received a Grammy nomination in the Best Musical Theater Album category.

Aggressive, charismatic hard rock frontmen such as Paul Stanley (of Kiss) and Freddie Mercury (of Queen) influenced Grönwall.

In 2009, Grönwall began working on his second studio album titled "Somewhere Between a Rock and a Hard Place" scheduled to be released on 2 June 2010.

He made his acting debut in America in the live televised concert rendition of Andrew Lloyd Webber and Tim Rice's Jesus Christ Superstar as the apostle Simon Zealotes on 1 April 2018, Easter Sunday.

A video for the track was launched on 5 January 2022, featuring project guest musicians Robban Bäck (Mustasch, ex-Eclipse, ex-Sabaton, ex-Ammunition) and Dave Dalone (also former bandmate in H.E.A.T.)

In March 2022, Grönwall announced that he would be joining American heavy metal band Skid Row as their new vocalist, replacing ZP Theart.

[4] Grönwall, known for his powerful voice, faced health problems, including a diagnosis of acute lymphoblastic leukemia in March 2021.

However, during his time with the band, he contributed to the album The Gang's All Here, released in October 2022, marking Skid Row's return to the studio after sixteen years.