Youth Although born in
Vanderbijlpark, Van der Merwe grew up in
George, where he played rugby for
Outeniqua High School to win inclusion in the Under-16 side for the 2007 Grant Khomo Week and their Under-18 side for the 2008 Academy Week and 2009
Craven Week competitions. In 2010, he moved to
Potchefstroom where he represented the and university side . He was a regular for the side during the
2010 Under-19 Provincial Championship competition, making thirteen appearances and in 2012, he made twelve appearances for the side in the
2012 Under-21 Provincial Championship, scoring six tries. He played
Varsity Cup rugby for the in
2013 and
2014. He made eight appearances and scored three tries in the 2014 competition, helping his side to the final, where they lost 39–33 to the , with Van der Merwe scoring a try early in the second half.
Leopards His senior debut came in 2013, when he was included in the senior side for the
2013 Vodacom Cup competition. He made his debut against the in
Johannesburg, coming on as an early substitute. He also marked the occasion by scoring a try in injury time at the end of the match. Two more starts and three more substitute appearances (and one more try) followed during that competition. His
Currie Cup debut came in July 2013. He came on as a substitute on the hour mark at
Olën Park in their
2013 Currie Cup First Division match against the eventual champions, the . While mainly being used as a substitute during the campaign (playing off the bench on eight occasions), he did one start in the competition against the . He made a further two appearances for the Leopards during the
2014 Currie Cup qualification tournament.
Lions In April 2014, Van der Merwe was a surprise inclusion in the touring squad for their Australian leg of the
2014 Super Rugby season. He made his
Super Rugby debut against the in
Hamilton and scored his first try for the Lions in their next match against the in
Dunedin. After one more match that he played off the bench (against the in Sydney), he made his first Super Rugby start in their final tour match against the in
Perth. His performances for the in
Super Rugby also led to a domestic move, with Van der Merwe joining the on a deal for the
2014 Currie Cup Premier Division competition. On 4 April 2015, he scored a last-minute winning in their
2015 Super Rugby season match against the to help the Lions win the match 22–18 against their trans-
Jukskei rivals. He made 15 total appearances for the club during this season. He joined on a short-term deal for the start of their
2015–16 Top 14 season. He played two games in total for Racing, against
Grenoble and
Oyonnax. Van der Merwe then returned to the Lions for the start of the
2016 Super Rugby Season, scoring 5 tries during the course of the season as the Lions reached their first ever
Super Rugby final. He came off the bench in the Lions loss to the
Hurricanes. At the conclusion of the
2017 Super Rugby Season Van der Merwe again came off the bench in the final, which saw the Lions defeated by the
Crusaders.
Sharks Prior to the start of the
2018 Super Rugby Season he moved to the
Durban-based
Sharks franchise on a two-year contract. In his inaugural season he made 15 appearances and scored 2 tries. Van der Merwe started at hooker as the Sharks fell to the Crusaders at the quarter-finals stage of the competition. He also scored a try in the
2018 Currie Cup final, which saw the Sharks win their first Currie Cup title for 5 years. He made only 8 appearances for the Sharks during the
2019 Super Rugby Season. The most notable event of the season came during a Sharks home game against the
Bulls, which saw Van der Merwe sent off following an altercation with
Springbok hooker
Schalk Brits. He received a three-week playing ban following the incident.
Sale Sharks Following the conclusion of his contract with the Sharks, Van der Merwe joined
Premiership Rugby side
Sale Sharks on a three-year contract. Sale Sharks announced in June 2023 that he had agreed early release from his contract and would be leaving the club with immediate effect and return to South Africa.
Bulls In July 2023 the
Bulls confirmed he had agreed a three-year contract until 2026. ==Honours==