The 30-year-old helped guide his team to three consecutive road wins, including a 1-0 victory over the Los Angeles Galaxy that snapped a 29-game home unbeaten streak in all competitions.
Ousted then stopped two penalties in a 2-1 win over the New York Red Bulls, before last weekend's triumph by the same margin over New England that included eight saves to halt the Revolution's 19-game unbeaten run at home.
"I think it's a team award," Ousted said after Thursday's practice. "Winning games away from home and having a good road form here definitely helped me to get that. It means a lot to me."
The Dane, who joined the Whitecaps partway through the 2013 season, was twice named to the MLS team of the week in June and is tied for second in the league with seven shutouts.
"Credit to him. I think he deserves it. I think he's been outstanding. It's nice for a goalkeeper to win that award," said Whitecaps head coach Carl Robinson. "Last year he was outstanding as well. He wants to get better. He challenges himself on a daily basis and I'll challenge him as well."
Ousted collected 37.9 per cent of the vote, beating out Toronto FC midfielder Sebastian Giovinco (20.4 per cent), Philadelphia Union striker C.J. Sapong (15.6 per cent), Portland Timbers striker Fanendo Adi (14.1 per cent) and San Jose Earthquakes midfielder Matias Perez Garcia (11.8 per cent) in a fan vote on the league's website.
"It's nice to get that praise, but even more (important) is getting the praise from the guys just means the world to me," said Ousted. "Having them saying they trust me is the best compliment a 'keeper can get."
Ousted is the second member of the Whitecaps to earn player of the month honours this season after striker Octavio Rivero took home the award in March.
Vancouver leads the Western Conference with 32 points and concludes a season-high five-game road trip on Saturday against the Colorado Rapids.
"Hopefully we can make him do less work so he doesn't have to win it again next month, but it's a credit to the team, the group," said Robinson. "We win together, we lose together. You win your individual awards, but it's about the team because we haven't conceded that many shots and he's not conceded that many goals."
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