Charlie Bertrand and Tim Towler scored four goals apiece to lead the Warriors (15-3) to their first-ever NCAA final.
Max Allen's unassisted goal with 16 seconds left in the second quarter punctuated the 11-goal run that put Merrimack ahead 11-1 at halftime.
The Panthers (15-4) applied full-field pressure in the third quarter, during which the teams combined for 15 turnovers. In desperation mode, they pulled to within 15-9 with 5:11 remaining in regulation before Kyle Stenberg and Towler applied the finishing touches for the Warriors.
Bertrand added two assists for a game-high six points. Merrimack, making its fourth NCAA tournament appearance, now will vie for its first national title. The school has only won two NCAA championships in any sport, in men's ice hockey in 1978 and softball in 1994.
"The job's not done. We want to win a championship," Warriors coach Mike Morgan said afterward in video interview posted on the Merrimack athletics website. "By no way, shape or form are we going to leave here today feeling like going there is enough. This hasn't sunk in yet. It's a great group of guys. We knew how special they were as the year went on."