Esterhuizen, who made his international debut in the T20I series in New Zealand last month, will replace Tom Banton who has had to withdraw from the tournament due to a finger injury.
The 24-year-old Esterhuizen impressed against the Black Caps in the five-match series, hitting 200 runs at an average of 50 and a strike rate of 145.98 that included two half centuries.
He picked up the player-of-the-series award as the Proteas beat the hosts 3-2 in the series.
Esterhuizen has played for Pretoria Capitals and MI Cape Town across the first four seasons of the SA20 in his home country.
Gujarat have had a mixed start to their 2026 IPL campaign, winning two and losing two of their opening four matches.
Kagiso Rabada took three wickets while Shubman Gill struck 86 to lead Gujarat Titans to a third victory of the season as they beat Kolkata Knight Riders by five wickets in Ahmedabad.
Mumbai Indians head coach Mahela Jayawardene says his team need to find a "spark" after they slipped to their fourth consecutive defeat in this season's Indian Premier League.
In a classic Wankhede run-fest on Thursday night, Punjab Kings produced a clinical chase to dismantle Mumbai Indians by seven wickets with 21 balls to spare in IPL 2026's 24th match.
Royal Challengers Bangalore secured their fourth victory of the Indian Premier League season after beating Lucknow Super Giants by five wickets at the M Chinnaswamy Stadium.
