Police have arrested a 41-year-old man on suspicion of robbery after the hold-up at Ladbrokes in Portland Road, Hove, at 3pm yesterday.
A man entered the shop and threatened a member of staff with a knife who handed over cash.
The suspect, from Brighton, was arrested shortly afterwards and is currently in police custody.
Detectives are not currently linking this incident with other recent robberies in the area.
Anyone who believes that they may have information which could help officers with their inquiries is asked to contact Sussex Police on 0845 6070999 or call the independent charity Crimestoppers on 0800 555111.
LIKE WHAT WE DO? HELP US TO DO MORE OF IT BY DONATING HERE.