In the biggest celebrity union since California legalized same-sex marriage, DeGeneres, 50, and de Rossi, 35, wed Saturday night in an intimate ceremony at their Beverly Hills home, People and Us Magazine reported.
A publicist for DeGeneres didn't immediately respond to messages from The Associated Press on Saturday.
After the California Supreme Court's ruling in May, the talk-show host announced that she and de Rossi would wed after four years together.
The ceremony was attended by 19 guests, including DeGeneres's mom Betty and de Rossi's mother Margaret Rogers, who flew in from Australia for the occasion, People.com reported Saturday night.
DeGeneres said after winning her fourth consecutive Daytime Emmy for talk show host in June that a date had not been set, and that she would show "a tiny bit" of the nuptials on her show.
While opponents in California have gathered signatures to put a measure on the November ballot for a constitutional amendment to ban gay marriage, Hollywood was throwing it support behind the newlyweds.
"One of my favorite people of all time is Ms. Ellen DeGeneres," Katherine Heigel told AP Television at a Hollywood charity event on Saturday night. "So I wish all the best, all the happiness, all the joy that comes with that certificate ... just the joy of being able to stand up and say that. In front of everyone you love and care about in front of each other and to walk away legal is huge."
Tila Tequila, whose dating reality show fame is built somewhat upon her affinity for both men and women, passed along her good wishes - with only one small complaint.
"I love Ellen (DeGeneres) I watch her show all the time," Tequila told AP Television. "I just want to say congratulations and I am really sorry you didn't invite me to your wedding."