The Modern Family actor confirmed his marriage plans with lawyer boyfriend Justin Mikita in a new YouTube video.
"It's true, I popped the big Q," Ferguson says in the clip as part of his new foundation Tie the Knot.
The organisation supports the continued fight for marriage equality in America.
"I said yes!" Mikita answers to Ferguson in the video.
The pair have been dating for just under two years, and have stated their hope that their marriage will eventually be recognised as official throughout the whole country.
Ferguson and Mikita have also partnered with Tie Bar to create a new collection of bowties, in order to raise money for various gay and lesbian equality organisations.
The Modern Family star was one of several celebrities who celebrated the San Francisco court's ruling that California's ban on same-sex marriage was "unconstitutional".