In his tweet, he said, "I entrust little Charlie to the Father and pray for his parents and all those who loved him."
His parents confirmed that Charlie had died in a hospice yesterday after a long battle with an extremely rare genetic condition causing progressive brain damage and muscle weakness.
In a statement issued on Friday evening, his mother Connie Yates said: "Our beautiful little boy has gone, we are so proud of you Charlie."
Tributes include a message from Prime Minister Theresa May, who said: "I am deeply saddened by the death of Charlie Gard. My thoughts and prayers are with Charlie's parents Chris and Connie at this difficult time."
The US Vice-President Mike Pence tweeted: "Saddened to hear of the passing of Charlie Gard. Karen & I offer our prayers & condolences to his loving parents during this difficult time."
The Great Ormond Street Hospital, where Charlie had spent a great deal of time receiving treatment,
said it sent its "heartfelt condolences" to Charlie's parents and loved ones.
The 11-month-old had been the focus of a lengthy legal battle between doctors and his parents, who wanted to take him to America for experimental treatment.
Charlie's parents had spent five months fighting a legal battle in which judges from the High Court, Supreme Court and the European Court all agreed with doctors that the treatment would not benefit Charlie.
His case attracted millions of supporters - including the Pope and President Trump.