Johnson, Kudla, Baker and Jack Sock were on the provisional entry list released by the International Tennis Federation last month, with their participation contingent on either playing Davis Cup or a successful appeal.
The 26th-ranked Sock is taking part in the Davis Cup quarterfinal against Croatia this week. Johnson is No. 25, Kudla is 102nd and Baker 179th.
Twins Bob and Mike Bryan were already set for the team and will look to repeat as doubles gold medalists. Johnson and Sock will be the other United States doubles pairing, the U.S. Tennis Association said Friday.
The American women's players were already set as well: Serena Williams, Venus Williams, Madison Keys and Sloane Stephens in singles and Coco Vandeweghe and Bethanie Mattek-Sands in doubles. The Williams sisters will also be seeking their fourth doubles gold medal.
The two U.S. mixed doubles teams will be announced at a later date.