The six-year-old Sunderland fan, who has the rare childhood cancer neuroblastoma, asked to have a party with his cousins and girlfriend on Friday.
Defoe then paid the youngster a visit, and lay in bed cuddling him.
Bradley's family posted pictures of the youngster snuggled up to the football player, and the bed party on Facebook.
An accompanying post on the Bradley Lowery's fight against Neuroblastoma page said: "Update on brad is....he is very weak and finding breathing difficult but he is fighting it. He insisted on having a party and he invited his cousins and girlfriend poppy yesterday.
"They all laid on the bed having cuddles I think it was his way of saying his goodbyes. Late last night his best friend jermain come (sic) to visit him and it was so heartwarming seeing how Bradley reacted .
"He was so happy and laid for ages getting cuddles. Bradley was really relaxed with him.
"Thank you again for your support, although we are getting a lot of messages and comments, we are going to get through them all eventually, as your words do really mean a lot to us all x x."
On Friday a post on the page warned people to be aware of fake pages, including false JustGiving pages, created in Bradley's name.
Earlier in the week an update informed wellwishers that the boy's condition was "deteriorating fast".
The youngster's family, from Blackhall, County Durham, have used social media to regularly update his many thousands of well-wishers around the world about his condition.
Bradley was a mascot for Sunderland several times last season and struck up a remarkable friendship with top scorer Defoe.
He was also a mascot for England at Wembley when his "best friend" scored in a World Cup qualifier against Lithuania in his comeback game.