Wiaan Mulder contributed to Leicestershire history in July 2022, with his career-best 235 not out against Sussex at Hove. His innings contributed to a Championship-record fifth-wicket stand of 477 alongside Colin Ackermann (277 not out) as well as Leicestershire's highest team total in first-class cricket, 756 for 4 declared.

As an allrounder, Mulder peaked for the season in the Royal London Cup in August, making 533 runs at 88.83 and taking 14 wickets at 28.92, as Leicestershire reached the knockout stages of a List A competition for the first time in 14 years. His performances were capped with a brace of career bests with both bat (116 not out) and ball (4 for 47) in the victory over Middlesex at Radlett.

His efforts earned him a recall to South Africa's Test squad for the concurrent tour of England, as an injury replacement for Rassie van der Dussen, and he added to his ten previous caps in the series decider at the Kia Oval in September.