In Hartford, Cullen worked to overcome the team's fans' disappointment at losing Francis. The Hartford fans initially booed him to show their dissatisfaction with the trade. He scored 16 points in 13 regular season games to finish the season with 110 points combined between the Penguins and Whalers, and was the team's best player in their first round loss to the Boston Bruins in the 1991 Stanley Cup Playoffs. He initially accepted an invitation to join the Canadian team at the 1991 Canada Cup, but subsequently chose not to participate as his contract had expired, leading to greater insurance concerns. Still without a contract when the 1991–92 season began, Cullen missed the first four games before signing a four-year deal with Hartford worth a total of $4 million. He returned to score 77 points in 77 games in his first full season with the Whalers and represented the team at the 1992 All-Star Game.