"Oh. It looks as though a certain cat is out of a certain bag," he wrote. "I'm very very happy of course but had hoped for a private wedding. Fat chance!"
He added, "Thank you all SO much for your kind congratulations. Deeply touched xxx."
Stephen and stand-up comedian Elliott, 27, were first pictured together in November, but are believed to have started dating in the summer. Friends of the star, who has spoken openly about his struggles with drugs and depression, have credited Elliott who giving him a "new lust for life".
Oh. It looks as though a certain cat is out of a certain bag. I’m very very happy of course but had hoped for a private wedding. Fat chance!— Stephen Fry (@stephenfry) January 6, 2015
"We've got the old Stephen back," a source told the Sun. "He has found new hope in Elliott and they thrive off each other."
Another friend told the Mirror, "Stephen and Elliott get on brilliantly together. It's fantastic to see Stephen with a smile on his face again. He has been very, very open about his battles with drugs and depression. Elliott seems to have given him the confidence to life his life again. It's great to have the old Stephen back."
Thank you all SO much for your kind congratulations. Deeply touched xxx— Stephen Fry (@stephenfry) January 6, 2015
Documents show that Stephen has given formal notice to marry Elliott at a register office Dereham, Norfolk, near to where he grew up.
His personal assistant added, "Stephen Fry is very happy and proud to say that he has set the wheels in motion for a wedding sometime in the future, but no date has been set due to a busy work schedule."