Most Rev Justin Welby says he is praying for Her Majesty the Queen and the royal family as concern mounts over her health.
"My prayers, and the prayers of people across the Church of England and the nation, are with Her Majesty The Queen today," Archbishop Justin wrote on twitter.
"May God's presence strengthen and comfort Her Majesty, her family, and those who are caring for her at Balmoral."
On Thursday, Buckingham Palace said the Queen's doctors had recommended her to remain under medical supervision.
"Following further evaluation this morning, the Queen's doctors are concerned for Her Majesty's health and have recommended she remain under medical supervision."
"The Queen remains comfortable and at Balmoral," a statement said.
The Duke of Cambridge, Prince Charles, and The Duchess of Cornwall are all traveling to Balmoral to be with her.
It's understood the Princess Royal is at Balmoral, and the Duke of York and the Earl and Countess of Wessex are on their way to the Queen's Scottish home.
The Monarch, 96, had to pull out of the Privy Council on Wednesday after doctors advised her to rest.
The head of the Catholic Bishops' Conference of England and Wales, Cardinal Vincent Nichols also took to Twitter to share his concern for the Queen's health.
"I am concerned to hear the news about Her Majesty The Queen's health.
"I offer my prayers for her and her family. May the blessings of the Lord strengthen and comfort her and her family," he wrote.