While not on the scoresheet in Friday's record-breaking 60-3 demolition of the Dragons in Wales, the Canadian winger has established himself as a fans' favourite thanks to his high-octane performances since signing for the club in 2009.
The 26-year-old arrived in Glasgow via Saracens, having made his debut for the Canadian national side three years earlier, and has since built a reputation as a fearsome finisher.
Van der Merwe now just needs two more touchdowns to become the Warriors' all-time leading try scorer, having already surpassed the total achieved by the likes of Thom Evans.
The Canadian has scored eight tries in nine appearances this season and admits he is happy at the Scotstoun-based club.
He said: "This was a pretty easy decision for me and I'm extremely happy to have signed the deal.
"The direction the squad is heading played a big factor in my decision to stay in Glasgow.
"I've been lucky enough to play in a couple of semi-finals with this club and it would be great to take it that one step further on. This squad definitely has the potential to win some silverware.
"We're a young team but there's a lot of talent and experience despite it being a pretty young squad so if we keep the group together, that's going to be great for the club in the long-term."
Warriors head coach Gregor Townsend said: "Any team would want to have a player of DTH's calibre in their ranks.
"He's strong, quick, and has a very good understanding of the game, so it's great that he will continue his career and development here at Scotstoun."