The company, which also produces explosives, said headline earnings per share (HEPS) - the main profit measure used in South Africa - rose 154% to 391 cents for the year ended March 31, compared with 154 cents a year earlier.
Omnia, which last paid a dividend in 2018, declared a final dividend of 200 cents per share and a special dividend of 400 cents per ordinary share.
"The Group's balance sheet has placed Omnia in a strong financial position, allowing us to resume dividends and return over 1 billion rand to our shareholders," said Omnia chief executive officer Seelan Gobalsamy.
High commodity prices and a bumper crop boosted operating profit for its agricultural division, while its chemical business also saw improved sales towards the latter part of the financial year.
However, COVID-19 lockdowns where it operates, extreme wet weather in some regions and new entrants in the market weighed on its mining division with operating profit down to 287 million rand ($20.07 million) from 356 million rand a year earlier.
Increased cash and proceeds from the sale of its Oro Agri division to agricultural services firm Rovensa for $146.9 million in 2020 further bolstered its balance sheet.
With net cash of 1.3 billion rand, the company said it was setting its sights on growing its agricultural operations in Brazil and Australia and expanding its explosives operations into Australia, Indonesia, Canada and the United States.
"We will use some debt to fund and expand our operations and as we find those opportunities we will decide what the appropriate capital core will be for those operations," Gobalsamy said.
($1 = 14.2980 rand)
(Reporting by Akhona Matshoba; Editing by Tanisha Heiberg, Robert Birsel)