And it's not just his influence on the pitch that will be missed, having proved an unshakeable character in the dressing room for Munster, Ireland and the British & Irish Lions over the course of his career.
Moves have been made to mitigate his departure, with former Australia lock Mark Chisholm arriving from Bayonne and Tomas O'Leary returning after a three-year absence to add experience to the core of the squad.
However, Foley insists O'Connell was not the only strong voice in the camp - and fully expects the likes of Peter O'Mahony and Denis Hurley to carry on from where he left off.
"You always have to be careful trying to fill something that's been there, you don't want to artificially fill it - you want people to grow into a position as well," said Foley, speaking at the GUINNESS PRO12 launch at the DIAGEO headquarters on Monday.
"We don't want people thinking 'this is the way Paul did it last year', people should be finding their own role.
"Peter (O'Mahony) has been captain for a few years now so it's important that he develops as well. We have other lads in our squad that are leaders as well, Denis (Hurley) behind him has proven that beyond shadow of a doubt, and we have other guys underneath that as well.
"We can't have one person as the beacon the whole time, but we've had immense leaders around Paul too.
"Knowing Paul would be leaving, we started searching a while ago to find a player of a quality that would fit into our group.
"You look at the rugby, the athletic ability, the experience and you find out about the character of a player. We were fortunate enough to speak to a few people who know Australian rugby and Mark Chisholm, and he's experienced, durable and captained Bayonne last year."
Munster were made to undergo a summer of introspection after their resounding 31-13 defeat in last season's final but in many ways it was a year of progress for the Irish province.
They had not reached the GUINNESS PRO12 Final since lifting the trophy in 2011, though Foley is not leaving anything to chance.
"You look at the game in even greater detail when you suffer a defeat, and we've really picked through it with a fine-toothed comb just to think about where we are and what we can or can't control around our performance," added Foley.
"It's important you start from zero again like everyone else and you try and get a Champions Cup spot, a top four, a home semi and try to get to a final - it's the process you go through and you all start from an even keel."
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