McDonald, the Blues' leading scorer before missing 24 games with a concussion, had an assist in his first game back and sparked a top line that scored twice in Friday night's 5-3 victory against St. Louis.
The Blues had totaled six goals the previous three games, all losses.
"I thought Andy had a real solid night for the first game back," coach Davis Payne said. "It's not easy to do, to jump back and play at that level."
T.J. Oshie scored his second goal in six games back from a broken ankle and Ty Conklin made 28 saves while filling in for Jaroslav Halak, who's day-to-day with an upper-body injury sustained in the Tuesday morning skate before that night's game against Colorado was postponed by a winter storm.
Payne said Halak's injury wasn't serious, but wouldn't provide any details.
"He tried to work through it, tried to get himself ready to go today, and wasn't able to," Payne said.
It was the Blues' first game in nine days due to the All-Star break and Tuesday's postponement, and got them off to a good start in February after a 2-8-2 January that dropped them to 13th in the Western Conference.
"We've put ourselves in a spot where we have to focus game by game and not look too far ahead," said Alex Steen, who had two assists. "At the end of the day whatever happens in the league is not in our hands. We got the W and we move forward."
Andrew Cogliano had two assists for the Oilers, who've lost 17 of their last 20. Edmonton rallied from three goals down to get within 4-3 on scores from Taylor Hall and Theo Peckham late in the second period. But the Blues answered on Brad Winchester's goal off a rebound early in the third.
"It was a weird game," goalie Devan Dubnyk said. "It just seemed like every chance the puck could go in the net for them it seemed to find a way in."
McDonald was injured near the end of an overtime loss at Edmonton on Dec. 4, crashing into Shawn Horcoff after getting his skate stuck in a rut. At the time, McDonald was the Blues' leading scorer with 17 points.
"Having Andy in the mix helps us a ton," linemate Brad Boyes said. "He was moving, he was getting back into what he does, controlling the puck and making good plays. I think our line played in the offensive zone for the most part, and a couple goals, too."
The Blues got first-period goals from Oshie and Alex Pietrangelo to take a 2-1 lead after the first 20 minutes. Matt D'Agostini scored on a power-play deflection, capitalizing on Jim Vandermeer's double minor, and Boyes nudged the puck over the line after Erik Johnson's shot deflected off Patrik Berglund to make it 4-1 at 13:46 of the second.
"It's tough to see how fast it's going in," Boyes said. "I'll take a little heat for it, par for the course, I guess," Boyes said. "
Hall answered 50 seconds later with his 17th goal and third in five games, and Cogliano scooted across the slot and handcuffed Conklin to set up Peckham's tip-in that cut it to 4-3 with 1:08 left in the second.
The Blues restored order in the third, outshooting Edmonton 13-9.
"I think with a young team that's gone through some losing it can tend to be pretty fragile in those tight games," said Oilers center Sam Gagner, who scored in the first period. "We've got to find a way to really push back."
Material from team media and wire services was used in this report