FirstRand said diluted headline earnings totalled 159.1 cents in the six months to end-December, from 131.2c a year earlier.
Headline EPS, the main measure of profit in , excludes certain one-time items.
The results were expected after FirstRand said last month that earnings could rise as much as 22%.
Net interest income, or earnings from lending, increased by 22% to R12.38bn driven by growth at its retail unit.
Non-interest income, which includes fees and commissions, grew by 13%.
South African banks are struggling to boost lending as corporate demand for credit remains slack and while many households remain under pressure, given rising fuel costs, high unemployment and weak growth in 's largest economy.
Smaller rivals Barclays [JSE:BGA] recently reported a 14% increase in full-year earnings, while Nedbank [JSE:NED] posted a 15% rise.
Leading lender Standard Bank Group [JSE:SBK] is scheduled to report on its performance on Thursday.
All four banks are expanding operations in , where burgeoning economies are beckoning investment from across the globe.
Shares of FirstRand are down 3.9% this year, underperforming a 2.6% rise in 's benchmark Top-40 index.