With coach Tony Smith choosing to rest several first-team regulars ahead of a trip to Catalan Dragons on Monday, it was left to the likes of O'Brien and 17-year-old debutant Ben Currie to get Warrington back to winning ways following a defeat to St Helens in their previous outing.
Despite going 12-0 behind to Widnes in the early stages, Warrington soon fought back and ran out comfortable winners, with Chris Riley scoring three of the home side's eight tries.
"We started slow but we kept positive and stuck at our game plan," added O'Brien. "We built some pressure, particularly around the ruck.
"Our forwards were outstanding. They set the platform for myself and Richie (Myler) and we finished off some good tries."
Meanwhile, Widnes remain bottom of the table after another heavy defeat.
"That's been the nature of our season," said Vikings coach Denis Betts. "It was so near and yet so far.
"There are things to improve on and things to maintain longer within our game.
"In the last two or three minutes, they got 12 points from a couple of slack attacking elements on our part, giving them field position.
"We showed that there's some flair in us, but we're making it very tough on ourselves."
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