GM will also commit to investing an additional $1.35B - a commitment previously made by Softbank.
GM will buy a $2.1 billion stake in its Cruise subsidiary, about four years after the Japanese investment group joined the carmaker is betting on driverless-car technology.
GM also said on Friday that it would invest an additional $1.35 billion in GM Cruise Holdings LLC, replacing a prior commitment from SoftBank.
After the transaction is finalised, GM will hold about 80% of Cruise, and SoftBank will no longer have an ownership stake in or rights to Cruise.
For years, investors have speculated that GM may split off Cruise. Some analysts have questioned if Cruise CEO Dan Ammann’s unexpected resignation in December was an indication that GM intended to retain the firm in-house for a more extended time than investors had anticipated.
“Cruise will continue to operate as it does today—an independent company working alongside GM in a flexible, collaborative partnership,” Cruise Chief Executive Kyle Vogt said. Mr Vogt, Cruise’s founder, was named CEO last month.