The company expects to pay £125m for 75 per cent of Folhamatic.
The rest of the equity will be retained by Folhamatic founder and chief executive Mauricio Frizzarin, who will continue to run the business, Sage said.
Sage software is used by more than 6m small and medium enterprises (SMEs) and it aims to tap in to the 90 per cent of Brazil’s SMEs that do not yet use any business software.
“[The deal] provides us with a market-leading position in the large and rapidly growing Brazilian market,” chief executive Guy Berruyer said.
The company added that the acquisition would immediately boost earnings per share.
The deal values Folhamatic, which increased revenues 13 per cent to £42.4m last year, at 13.4 times forecast 2012 earnings, Sage said.
Shares in Sage closed up 5.44 per cent at 267.5p yesterday, having fallen nine per cent since it reported last month that first-half revenue growth had slowed to two per cent.
Milan Radia, an analyst at Jefferies, said it made sense for Sage to increase its presence in fast-growing regions such as Brazil, adding that the company was paying a “fair price” for an asset with some unique qualities in the market.