The duo were two of the star performers on the triumphant tour to Australia and their subsequent arrival at Franklin's Gardens is a major coup for the Aviva Premiership finalists.
North was the Lions' most dangerous back throughout, scoring a stunning solo try in the first Test, while the scrummaging prowess of injury call-up Corbisiero was instrumental in the series victory over the Wallabies.
Mallinder watched the events in Australia unfold with elation as his decision to sign the pair was vindicated and he has demanded they deliver for Northampton as well.
"We watched the Lions tour with excitement, seeing what George and Alex accomplished," he said.
"They're good signings on paper and the important thing for us is that they're good players for Northampton. That's the challenge we face.
"George had a really good tour, not just the odd top game. In every game he played he had a massive impact. We're hoping he can do that for us.
"Corbisiero is a bright bloke who loves to talk about the scrum. He's very enthusiastic about it.
"On top of that, he's also a very good player. That's the type of player we want.
"You can't just have scrummages now, they have to be able to do other things around the field. That's one of the advantages of Corbisiero."
Mallinder denies the recruitment of North and Corbisiero has heightened expectations at Northampton, who were beaten 37-17 by Leicester in last season's Premiership final.
"I don't personally feel the pressure is any greater now. The Northampton faithful are quite demanding, they know their rugby and they want success," he said.
"The pressure and expectation is always there. We've made six finals in six years, so we're doing something right.
"But everyone at the club is motivated to go that one step further and win something major."
- Sports & Recreation
- Aviva Premiership