Cory Schneider made 29 saves for New Jersey (22-11-7), which lost its fourth straight game.
Brian Boyle gave New Jersey a 1-0 lead on the power play with 14 seconds left in the first period when he tipped a pass from Taylor Hall. The goal came 15 seconds after Schneider made a shorthanded breakaway save on Tyler Pitlick.
Radulov tied it 1-1 at 6:18 of the second period after Devils defenseman Andy Greene made an errant pass to the Stars forward in front of the net.
"I was trying to make a play there," Green said. "I thought I saw we had a guy in front there. Obviously we didn't and they made us pay. It was kind of the theme of the night."
Ritchie gave Dallas a 2-1 lead at 11:07 of the second on the power play when he tipped a point shot by John Klingberg. The goal came after Devils defenseman Sami Vatanen took back-to-back penalties, including interference for playing the puck while his foot was in the penalty box.
"It's too hard to win in this league when you give games away," Devils coach John Hynes said. "That's not the way you want to lose games. It wasn't good enough."
Dallas took a 3-1 lead at 18:11 of the second when Seguin scored on the third chance of a shorthanded 2-on-1 with Jamie Benn for his 20th goal of the season.
"I love being on the [penalty kill], I've felt that extra responsibility since training camp, and since we first talked when [Ken Hitchcock] first got named coach here, he said I was going to get that opportunity," Seguin said. "I love doing it. Happy I got one."
Taylor Hall made it 3-2 with 28 seconds left in the period when his wrist shot rebounded off Bishop and Stars defenseman Greg Pateryn.
Janmark gave Dallas a 4-2 lead at 9:43 of the third period on a rush with Martin Hanzal after Radulov blocked a shot in the defensive zone. Kyle Palmieri scored on the power play at 15:59 to make it 4-3.
