Terms of the deal were not disclosed.
The acquisition adds 115 MetWest employees to TCW.
MetWest's Tad Rivelle, former MetWest chief investment officer, now serves as CIO of TCW's high-grade fixed-income group.
TCW fired Jeffrey Gundlach as CIO on Dec. 4; he has since launched his own firm, DoubleLine Capital, Los Angeles, with former TCW employees.
TCW, a unit of Societe Generale, first reached agreement to buy MetWest on Dec. 4, the same day as Mr. Gundlach's termination.
“Societe Generale is committed to developing TCW for the long-term,” Jacques Ripoll, head of Societe Generale's global investment management and services, said in a TCW news release. “The acquisition of MetWest ensures TCW will continue to have an extremely strong and attractive multiasset-class investment platform for its clients.”