Nassib, 28, thanked his coaches, teammates and the N.F.L. for their support.
“I would not be able to do this without them,” he wrote in his Instagram post.
The Raiders quickly showed their support for Nassib’s announcement, writing “proud of you, Carl” in a post to the team’s Twitter account that also included his original statement. The N.F.L.’s official Twitter account followed suit, with a message that read, “The N.F.L. family is proud of you, Carl.”
Nassib’s announcement was made during Pride Month, celebrated each June. He said he would donate $100,000 to The Trevor Project, a nonprofit group that focuses on suicide prevention efforts among lesbian, gay, bisexual, transgender, queer and questioning youth.
Michael Sam, a defensive lineman who played college football at Missouri, announced he was gay before he was chosen in the seventh round of the 2014 draft. The Rams, then based in St. Louis, cut Sam at the end of training camp. The Dallas Cowboys signed him to their practice squad, but he never played in a regular season game.
Sam’s draft status was seen as a barometer of whether the N.F.L. was ready to accept an openly gay player, particularly because the N.B.A. broke that barrier in February 2014, when Jason Collins joined the Nets.
