Cale Makar, Nicolas Roy and Devon Toews scored for the Avalanche, who are the No. 1 seed from the Central Division and Western Conference. Gabriel Landeskog had two assists, and Scott Wedgewood made 24 saves.
Joel Edmundson scored the lone goal for the Kings, the second wild card from the West. Anton Forsberg made 27 saves.
Anze Kopitar played the final game of his 20-year career, all with Los Angeles. The 38-year-old center announced on Sept. 18 that the 2025-26 season was his last in the NHL. Kopitar helped the Kings win the Stanley Cup in 2012 and 2014, and became the franchise's all-time leader in points (1,316) on March 14. He replaced Dustin Brown as captain prior to the 2016-17 season.
Colorado will play either the Dallas Stars or Minnesota Wild in the second round. That series is tied 2-2 after the Wild’s 3-2 overtime win on Saturday.
MacKinnon gave the Avalanche a 1-0 lead while on a power play at 13:13 of the first period. Nazem Kadri fed a cross-ice pass to MacKinnon in the left face-off circle, where he put a one-timer on net that trickled through Forsberg's pads. It was the first power-play goal of the series for Colorado, which had been 0-for-9 over the first three games.
Makar made it 2-0 at 5:48 of the second period. He skated in from the blue line past Kings forward Taylor Ward into the right circle and beat Forsberg with a wrist shot to the glove side.
Edmundson cut the deficit to 2-1 at 13:43 when his wrist shot from the left circle squeaked through Wedgewood.
Roy pushed the lead to 3-1 at 3:13 of the third period after Artturi Lehkonen caught a pass from Sam Malinski in stride into the offensive zone. Lehkonen took the initial shot and Roy put the rebound through the five-hole as he crashed the net.
Toews increased it to 5-1 at 6:01 with a wrist shot through a screen from the left circle into the top right corner.
MacKinnon scored an empty-net goal at 14:22 to secure the 5-1 final.
