Korean officials say 1,000 sq km (386 sq miles) will be developed – half for local farmers, half to produce processed goods for South Korea.
Seoul also signed a deal last year to lease a vast area of Madagascar.
Rich countries have increasingly sought farmland in poorer nations to help shore up food supplies.
Countries such as China, Saudi Arabia, South Korea and Kuwait are short of arable land and have been seeking agricultural investments in Africa.
But South Korea’s deal in Madagascar – which would have seen it lease an area the size of Belgium from the island nation – has been thrown into uncertainty.
Madagascar’s government was overthrown in a coup earlier this year and the new leaders said they would scrap the deal, which was cited as one reason for the unrest.
‘Colonialists’ gibe
The state-run Korea Rural Community Corporation says a memorandum of understanding will be signed with Tanzania next month.
The corporation says it will produce processed foods like cooking oil, wine and starch on the land.
Lee Ki-Churl, a corporation official, said he expected Tanzanians to benefit from the deal.
"Some African countries export fruit and import fruit juice, or export olives and import olive oil, simply because their past colonialists did not teach them how to process food," he told the AFP news agency.
"We plan to set up an education centre for Tanzanian farmers in the food-processing zone in order to transfer agricultural know-how and irrigation expertise to them."
He said about 100bn won ($83m) would be spent to develop an initial 100 sq km of land over the next few years.
South Korea’s Yonhap news agency reported that the corporation hoped to exploit deposits of iron ore, gold and copper in other parts of the Tanzania to help fund its project.
The deal comes weeks after Tanzanian Prime Minister Mizengo Pinda visited Seoul, when the two nations promised closer ties.