The firm's chairman Loic Tardy said the money would be spent on boosting domestic production and increasing the number of Wall's ice cream mobile stalls from 50,000 to 60,000 by the end of the year, reported The Nation newspaper.
The investment is a 66 per cent increase on last year's BT600 million.
Unilever wants to grow its share of the ice cream market to 46 per cent by the end of the year. The Wall's brand currently holds a 44 per cent market share, according to the report, leading the market that generated BT8.6 billion in sales last year, according to Euromonitor statistics.
Nestle followed, with a 32-per-cent market share at the end of last year.
Unilever has had an advantage with its early presence in the Thai market - its brands were among the first in the packaged foods segment. It has been the key player in ice cream for more than a decade prior to Nestle's entrance.
However there is room for competition in this sector, which is growing fast, albeit rising from very low consumption of an average 0.6 litres per person each year currently. In Bangkok, where packaged foods are significantly more popular, people eat close to 6 litres per year, however, and western brands are trying to tap this interest in convenience foods.
This year, the market is expected to grow by around 15 per cent but Unilever has ambitions for even faster expansion.
"With our aggressive marketing activities and the rollout of new innovations and flavours, we expect higher growth than the market at over 30 per cent this year," said Tardy.