Darby signed a contract with the 49ers on Saturday, Adam Schefter of ESPN reports.
With Brandon Aiyuk (contract) and Ricky Pearsall (hamstring) both not practicing early on in training camp, Darby will presumably be a high-upside camp body for a team suddenly devoid of pass catchers. A 2021 sixth-round pick by the Falcons, Darby played in just one game with Atlanta last year, primarily floating around on the practice squad.