"It was a shock [to learn I was going back to New Jersey], I really didn't see it coming, but it's a great opportunity," Sullivan told the Devils website. "I'm glad to be going back to where it all began."
The 38-year-old left wing has played 1,002 career NHL games spanning 17 seasons with New Jersey, Toronto, Chicago, Nashville, Pittsburgh and Phoenix.
"He provides depth at forward," Devils general manager Lou Lamoriello told reporters. "Like we've always said, you try to get better, but at what expense? So, we really did stand pat."
Sullivan, who signed a free-agent contract with the Coyotes in July, 2012, has 288 goals, 454 assists, 742 points and 583 penalty minutes. In 33 games with Phoenix this season, he's posted five goals, 12 points and a minus-8 rating. He will not be joining the team against the Boston Bruins at TD Garden on Thursday. He will undergo a physical in New Jersey and might be available to coach Peter DeBoer on Saturday against the Maple Leafs.
"I'm getting right back into the thick of things of a [Stanley Cup] Playoff race and it's definitely going to be refreshing for myself," Sullivan said.
Lamoriello said he and his staff contemplated what could and couldn't be done at the trade deadline.
"You spend a week of seeing exactly what can and can't be done," he said. "It comes down to the last two days and the last few hours and nothing was done and we thought that was in the best interest of the organization to do nothing.
"It's no different this time than any other time. We'll always try to get better and we've always tried to do things earlier. We've started to get our bodies back so you can't make a better trade than getting [Dainius] Zubrus back and, hopefully, Kovy [Ilya Kovalchuk] in a short period of time and we get our team together."
The Devils are 0-1-3 across their past four games and have scored nine goals during that span. For the season, New Jersey is No. 25 in the NHL with a 2.42 goals-per-game average through 36 matches.