Robinson, who caught 34 passes for 344 yards and two touchdowns for the St. Louis Rams last season, signed a one-year, $685,000 contract.
To make room on the 53-man roster, the Cowboys waived fullback Tony Fiammetta.
"There were two other teams that were really interested in him but when I mentioned the Dallas Cowboys, I could almost tell that his eyes were lighting up over the phone," agent Harold Lewis said.
Robinson, who was drafted in 2007 by the Atlanta Falcons, caught the Cowboys' eye during during two days' worth of joint practices with the San Diego Chargers during training camp.
He provides a game-ready alternative for the Cowboys when needed, as the Cowboys run an offense very similar to Norv Turner's attack with the Chargers.
Todd Archer covers the Cowboys for ESPNDallas.com.