Gravelle starred in the 2010 film Patagonia and then in the BBC Wales series Baker Boys as Rob, the co-manager of Valley Bara and the fiancée of Sarah (Eve Myles). In 2013, he was cast in the hit ITV crime drama Broadchurch as Joe Miller, husband of Olivia Colman's character. Later that year he guest-starred in the Welsh detective drama Y Gwyll, in which his real-life wife Mali Harries stars. He also starred with Harries in Keeping Faith/Un Bore Mercher (2017), where they played a married couple.