Ian Edwards, 36, of no fixed address, was sentenced at Lewes Crown Court on 6 July having pleaded guilty to supplying heroin and crack cocaine, according to Sussex Police.
Detective Sergeant Peter Yarrow of the West Sussex Community Investigation Team said; "Edwards' latest arrest was part of a long term operation in the Worthing area and involved collaborative working with colleagues from Brighton Prevention Enforcement Team.
"He was actively involved in supplying heroin and crack to some users in the town centre but our operation completely disrupted his activities. We are continuing our relentless work to disrupt criminals like Edwards who bring degradation and misery to vulnerable people."
Edwards was also on prison licence at the time of his arrest in December 2019, having been released part way through a 13 year sentence he had been given in 2013 for conspiracy to supply drugs, and has also been recalled to prison to serve the remaining part of that sentence, police said.
His new six and a half year sentence is to be served after to the remainder of the 13-year sentence.
For information on how you can help the fight against drug dealing in communities see the Sussex Police website.