The Canadian, 28, was picked as the Devils' forward of the year in 2016-17 after scoring 24 goals and 29 assists in 66 games.
Haddad was a dominant force last season, playing the role of a power forward as Devils won the Elite League.
"Joey Haddad was outstanding for us last season," said Devils player-coach Andrew Lord.
"There were a number of games that he completely took over or broke open a game for us and that is what makes fans love him so much.
"He is a big body and dominates in the corners and is tough to play against.
"There were a number of teams that wanted him to make a move but he loves it here and I don't really think he entertained any other offers."
Haddad will also be a vital part of Devils' Champions Hockey League campaign, with the Welsh side drawn in Group E against HC Davos from Switzerland, Bili Tygri Liberec of the Czech Republic and Sweden's Vaxjo Lakers.

Dr Christopher Davies, who works for the the Royal Berkshire Hospital, said a matron later purchased the item for £22.95 from Homebase instead.
Dr Davies, a respiratory consultant, said it was then fitted for free by in-house staff.
A hospital spokesperson said the quote was reviewed and "firmly rejected".
Dr Davies said the blackout blind "must have been gold plated" to warrant such a price, the Mail on Sunday reported.
He wrote: "So many posts about inadequate funding but here's an example of how the money is used... maybe it's not just about poor funding."
In a statement issued to the BBC, the hospital said: "In line with NHS requirements, the trust sought quotes for a blind which meets fire and infection control regulations.
"This particular quotation was reviewed by the management team and firmly rejected."
NHS England has been approached for comment and said it was looking into the situation.

The sisters-in-law have been named as Sharon Dodd-Archibald, 46, and Mary Archibald, 51, both from Glasgow.
They were found at the flat in Dalserf Court in the Gallowgate area on Sunday.
Their deaths are not being treated as suspicious. Police are awaiting the results of toxicology tests and post mortem examinations.
Following the discovery of the women's bodies at about 12:00 on Sunday, police said that one line of inquiry was possible carbon monoxide poisoning.
Although police will not formally rule that out until a cause of death has been established, it has emerged that no faults were found with the boiler during tests carried out by the Health and Safety Executive and Scottish Gas.
There are no other gas appliances within the flat.
Cardiff Devils attacker Joey Haddad has re-signed for a fourth season with the Elite League champions.
[NEXT_CONCEPT]
A senior doctor has spoken out after his hospital was quoted £855.80 for a blackout blind by its official NHS contractor.
[NEXT_CONCEPT]
The deaths of two women at a flat in Glasgow may not be due to gas poisoning after a boiler was found to be in working order with no faults.