De Klerk's inclusion in the squad increases the size of the group currently preparing for the first Test in Auckland to 36 players, after Springbok hooker Bongi Mbonambi remained behind in South Africa earlier this week to attend to family matters.
The livewire is the fourth scrumhalf in the touring squad after Grant Williams, Cobus Reinach and Morne van den Berg.
De Klerk was integral in the Boks' last two Rugby World Cup campaigns and played the full 80 minutes against New Zealand in the 2023 Final in Paris. A spate of injuries hampered his career since that night, but the 33-year-old featured off the bench against Italy and Georgia this season.
The Canon Eagles player knows how to win in New Zealand as he was in the starting XV for the Boks' famous 36-34 victory in Wellington in 2018.
The Springboks will face their archrivals, the All Blacks, at Eden Park in Auckland on Saturday 6 September, before travelling to Wellington for their second match on the tour at the Sky Stadium on Saturday 13 September.