Former Apprentice contestant Hopkins was banned from the social network in 2020 for breaking its rules on “abuse and harmful contact”.
Robinson, the former leader of the English Defence League, also had his account shut down in 2018.
Yesterday evening Hopkins tweeted: “Thank you Elon Musk and thank you to all the Twitter family who have brought Tommy and I back to X.
“Know this. You are not alone. We are many. And we are stronger together.
“The fight for your freedom is back on.”
Robinson’s first Tweet since getting his account back was a clip from David Hasselhoff’s 1989 song Looking For Freedom – with his own face imposed over the Hoff’s.
He added: “I am grateful to Elon Musk for giving me my voice back at such an important time.
“I’ve been censored, attacked, slandered and imprisoned for shining a light on uncomfortable truths that our government wishes to hide.
“The public are now aware I was telling the truth. We have lots to do.”
Robinson later tweeted: “They were fearful of our ability to awaken the masses, they attacked us, they demonised us, they slandered us , they imprisoned us, but they never broke us.
“I’d like to thank everyone of you who supported me and refused to accept their lies.”
Robinson was jailed on July 11, 2019, for nine months for contempt of court after live-streaming a video outside a child grooming trial.
He was released after serving nine weeks in category-A Belmarsh Prison, south London.