The center led the Blues with NHL career highs in assists (49), points (77) and points per game (0.94) playing all 82 games, and he was second with 28 goals. O'Reilly ranked first among Blues forwards in average ice time (20:46) and was fourth in the NHL with 94 takeaways. His plus-22 rating was tied for seventh among NHL players who had at least 75 points.
O'Reilly had 23 points (eight goals, 15 assists) in 26 Stanley Cup Playoff games and was awarded the Conn Smythe Trophy as postseason MVP with the Blues, who won the Stanley Cup for the first time, defeating the Boston Bruins in the Cup Final in seven games.
He is the second Blues player to win the Selke (Rick Meagher, 1989-90), which is voted on by the Professional Hockey Writers' Association at the end of the regular season.
"He came as advertised. He's a great two-way player," St. Louis general manager Doug Armstrong said. "The number of face-offs he takes for us, he touches every point of our offensive and defensive game. He was a guy that like all great leaders, he led by example during the bad times and tough times, and then obviously when the going was the hardest in the playoffs, he was our leader and our best player."
The other finalists were four-time winner Patrice Bergeron of the Boston Bruins, who was eighth in the NHL this season in face-off winning percentage (56.6 percent, minimum 750 attempts), and Mark Stone of the Vegas Golden Knights, who led the NHL in takeaways (122 in 77 games).
Bergeron, a finalist for an eighth straight season, failed to win the Selke for a fifth time, which would be the NHL record.
"I remember when I first saw him break in the League and saw the player he was. He was someone I looked up to as someone I wanted to be," O'Reilly said of Bergeron. "Watching him throughout the years and how he impacts the game in every sort of fashion, everything he does, you learn from that. For myself, you try to take stuff that he does and try to carry it over. It's guys like that that it's impressive my name alongside on the trophy."
