The 18-year-old had spent two seven-day stints with Neil Lennon’s side as the Easter Road coaching staff ran the rule over the player.
Admitting it was a “dream come true” to sign professional terms, Block said: “Having spent time with Hibs, I know it’s the right move for me.
“But this is just the beginning. Now I need to work harder than I can ever imagine, listen, learn and place my trust in Hibs to help me to develop and be the best player I can become.”
Rocks boss Jack Pearce hailed Block’s work ethic and attitude, as the former Brighton youth player prepared to leave Nyewood Lane.
He told the Bognor Regis Observer: “Tommy’s success shows what playing for Bognor can do for a young player and we have to hope it will lead to others wanting to play for us.”
The teenager has been on the Capital club’s radar since last year, with club scouts watching him on more than one occasion.
Block revealed that he had been training with the first team at East Mains, and had scored in a bounce game during his first trial spell.
He also spent time with the club’s Under-20s in his bid to win a deal with Hibs.