The Vision Fund II will focus on AI-based technology and promises around $108bn in capital from more than a dozen investors.
SoftBank said that companies such as Microsoft, Apple, Standard Chartered Bank and Foxconn have agreed to invest in the fund.
SoftBank said it would invest around $38bn in the fund, more than $28bn it invested in the first fund.
The Japanese conglomerate launched its original Vision Fund in 2016, investing in firms such as Uber and WeWork.
At the end of March, the company pointed out how it had invest $64bn in 71 companies, including two it had exited.
SoftBank Chief Executive Masayoshi Son said he hopes to create a new fund every two to three years.