AFL.com.au understands Delaney, 24, informed the Roos of his decision on Friday, having met with the Saints, Lions and Blues earlier this week.
The Saints have already put an offer to 194cm, 99kg defender, while the Lions made an unsuccessful play for him in last October's trade period when he remained contracted to the Roos.
But Delaney is now out of contract and after playing 26 games in the past three seasons, believes he will enjoy greater senior opportunities outside Aegis Park.
North was keen to retain Delaney and AFL.com.au reported last month the Roos had made an improved offer in an attempt to beat off his rival suitors.
Delaney has struggled to get a game in the past two seasons whenever North's preferred two key defenders, Scott Thompson and Nathan Grima, have been fit.
The Roos re-signed Grima, 28, for 2014 two weeks ago.
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Delaney joined North in the 2009 rookie draft and showed in his limited AFL opportunities he can go toe-to-toe with power forwards such as Lions captain Jonathan Brown.
After playing 13 games in 2012, Delaney could not break into the senior team until round 19 this season despite outstanding form with North's VFL affiliate North Ballarat.
Delaney got his opportunity when Grima was ruled out of the Roos' 19 clash against Geelong with injury, and was a solid performer in North's final five games.
Delaney's younger brother Cameron, 21, is contracted at North to the end of 2015 and is another of the Roos' tall defensive options.
Luke Delaney's decision will boost veteran defender Michael Firrito's hopes of playing on in 2014.
But the Roos are also understood to be interested in out-of-contract Greater Western Sydney defender Josh Bruce and could now make a concerted effort to entice him to Aegis Park.
Twitter: @AFL_Nick.
