Champion, who hadn't previously acknowledged his sexuality publicly, revealed the news while attending MSNBC anchor Thomas Roberts' wedding to Patrick Abner.
"We're getting married New Year's Eve in Miami," Champion told the Times. His partner added: "We'll do it [in New York] officially, and then have a party in Miami."
GLAAD President Herndon Graddick congratulated Champion on his engagement. "Sam has been a good friend and longtime supporter, and I wish him and Rubern the absolute best," he said in a statement.