South Africa started well, but a lapse in concentration allowed Kenya a mini-comeback before the break. The second half belonged to the Bok Women though, who scored 53 points without reply as their pack took control of the match and the team found their groove on attack.
The Springboks scored three tries in the first 15 minutes to take a comfortable 19-0 lead, but on the negative side, they lost Lusanda Dumke (No 8) to injury midway through the half, while Nompumelelo Mathe (flanker) spent 10 minutes in the sin-bin.
The Kenyans struggled to cope with the host team's forward pressure early in the match, and as a result they conceded a number of penalties which allowed the South Africans to play in their opponents' half.
Grain (wing), back in the team for the first time since 2021, scored the first try in the third minute as the Bok Women controlled possession from the start. Six minutes later, Sinazo Mcatshulwa (lock) went over from a lineout maul, and then Yonela Ngxingolo (prop) powered her way over the tryline from a tap-penalty.
Libbie Janse van Rensburg (flyhalf) converted two of the tries, but Kenya started to find their rhythm and their discipline also improved as they fought back with two tries. Diana Kemunto (flanker) intercepted and ran 60m to score just after the first quarter, and 12 minutes later wing Stella Wafula exploited a lapse in defence by the Boks, with Mathe in the bin.
Roseline Botes (hooker) scored South Africa's fourth try - also from a great lineout maul - on the stroke of halftime to give them a 12-point lead.
Whatever was said at half-time in the changeroom clearly had the desired effect as Louis Koen's team shifted gear.
Fullback Byrhandré Dolf scored her maiden Test try before Danelle Lochner (lock) added her name to the score sheet - with the Boks showing more patience on attack - and when Botes scored her second try, the score jumped to a more respectable 41-12 with just under 30 minutes to go.
The Bok Women then took complete control of the match and ran riot in the final 25 minutes. Unathi Mali (wing) scored on debut and Janse van Rensburg also went over, with Mathe and Grain both scored two late tries each as the host team almost crossed the Kenyans' try-line at will.
Springbok Women 77 (24) - Tries: Veroeshka Grain (3), Sinazo Mcatshulwa, Roseline Botes (2), Yonela Ngxingolo, Byrhandré Dolf, Danelle Lochner, Unathi Mali, Libbie Janse van Rensburg, Nompumelelo Mathe (2). Conversions: Janse van Rensburg (5), Mary Zulu.
Kenya Lionesses 12 (12) - Tries: Diana Kemunto, Stella Wafula. Conversions: Grace Okulu.