The order would also approve Sprint's acquisition of wireless network operator Clearwire, which owns the rights to valuable swathes of wireless frequencies.
The FCC approval is the final obstacle to the pair of telecom deals.
SoftBank's acquisition of Sprint could pump more money into the company and help it take on industry leaders AT&T and Verizon.
Dish Network had pushed its own competing proposals for both Sprint and Clearwire, but recently abandoned its bid.
Dish had warned that allowing SoftBank, a Japanese company, to own such large U.S. telecommunications networks would pose a threat to national security. Sens. Charles SchumerCharles SchumerHow the candidates for DNC chair stack up ahead of Saturday's vote DNC candidate Harrison drops out, backs Perez for chairman Ellison holds edge in DNC race survey MORE (D-N.Y.) and John McCainJohn McCainWhy the GOP cannot sweep its Milo scandal under the rug New York Knicks owner gave 0K to pro-Trump group Hannity apologizes for sharing 'inaccurate' story about McCain MORE (R-Ariz.) also expressed concern about the SoftBank deal.
After SoftBank agreed to a series of concessions, an interagency panel cleared the deal of national security concerns in May.