Hyman had a goal and an assist, and Leon Draisaitl had two assists for the Oilers (30-18-5), who are 9-0-2 in their past 11 games. Jack Campbell made 26 saves for his eighth straight victory.
"Winning teams get contributions up and down the lineup through all three areas of the game: the power play, the penalty kill and 5-on-5," McDavid said. "We've been doing that and getting good goaltending, as well."
Erik Brannstrom scored his first goal in 121 games, and Claude Giroux extended his point streak to six games for the Senators (24-24-3), who had won four straight.
Anton Forsberg allowed six goals on 37 shots before leaving with an injury with 5:23 remaining. Forsberg had to be stretchered off the ice after Hyman was pushed into him during a scramble in the crease.
"It's awful," Hyman said. "I mean, you hear him going down and you hear him in pain, but you can't do anything. I literally couldn't do anything. I'm stuck on him because there's a guy who's on top of me pushing me in.
"It's not a fun play to be a part of. I almost stopped playing there because I locked eyes with him and he was just in pain. Hope he gets better soon. Just a tough, tough play."
Ottawa coach D.J. Smith did not have an update on Forsberg after the game. Mads Sogaard made three saves in relief in his season debut.
"Never a pleasant sight," Senators captain Brady Tkachuk said. "He's been great for us all year. No update, but I hope it's not as severe as it looks. Really hoping, really praying that it's not too bad."
McDavid gave Edmonton a 1-0 lead at 2:18 of the first when he banked the puck in off Forsberg from below the goal line.
Jake Sanderson scored 21 seconds into the second period to tie it 1-1. Skating in as the trailer on a rush, he received a cross-ice pass from Mathieu Joseph and scored five-hole with a wrist shot.
"I don't know how many great things I could say about that guy," Tkachuk said of Sanderson. "He changes our team, he changes our complexion, he's already unbelievable as a 20-year-old. I can only imagine the things he's going to accomplish throughout his career."
Hyman scored with a backhand deke on his first career penalty shot to put the Oilers back in front 2-1 at 1:44.