Carl Webb starred for the Cowboys with a powerhouse display while new buy Travis Burns had a strong showing at halfback as they beat the Raiders 32-30.
Canberra struggled to deal with the humid conditions but looked dangerous when spreading the ball wide to Adrian Purtell while Todd Carney had a strong return from a quad injury.
The Cowboys burst out of the blocks when O’Donnell crashed over and the lock forward was over again in the 13th minute after finding Canberra’s left-side defence wanting.
Canberra hit back when Colin Best pounced on a loose ball after an Aaron Payne pass went to ground but O’Donnell claimed his third for a six-point lead.
Canberra crossed again before the break with William Zillman sprinting 70 metres but Webb capped off a commanding first half with a try to ensure an eight-point lead at the break.
The early stages of the second half turned into a dour affair with both sides struggling to control the ball in the muggy conditions before Matt Bowen collected his own bomb to score.
After some continued pressure on the Canberra line, Steve Southern crashed over to make it a 20-point lead.
Cowboys Coach Graham Murray thought his side improved defensive showing was the key to victory.
“Our goal line defence was good and overall I thought it had improved heaps from the week before.
“They defended strong in the middle. The try line was good and they scrambled well for each other.”
Murray saved praise for the performance of his halves.
“Justin Smith is a true professional, he is a great defender and not frightened to take the ball to the line and I think he and Travis Burns combined well.
“I thought Travis and Matt Bowen were a bit more in sync while I thought our two hookers were really good.”
Canberra coach Neil Henry was to left rue last minute injuries to key players.
“I don’t think we were particularly good, a few things conspired against us.
“Joel Monaghan, Neville Costigan and Joe Picker were all late withdrawals but we did have six players down to a two man bench and you don’t expect that.
“I had a lot of players out of position and we didn’t handle that too well. You’ve got to be able to fall back on some basic structure.”
Henry was however able to find some positives out of the performance.
“I was very pleased the way William Zillman came back. He’s back a few weeks early while Joel Thompson did well filling in all over the park.”