The 27-year-old had a medical in London on Friday morning after agreeing terms with the League One promotion chasers.
Stockley has had limited game time this season, with him in a similar boat to PNE team-mate Josh Harrop who joined Ipswich Town on loan earlier in the week.
He's only started four times in the Championship in 2020/21, coming off the bench 12 times. His one goal was a stunning long-range finish against Birmingham in October.
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There's been plenty of interest of him this month, with five clubs enquiring about him - Bristol Rovers managed by his former Exeter boss Paul Tisdale being one of them.
One of the clubs interested wanted to sign him permanently but Stockley preferred the Charlton loan.
Stockley was a £750,000 signing from Exeter City in January 2019.
His time at Deepdale has seen him start 21 league games and make 44 substitute appearances. In addition, he's played six times in the cup competitions.
North End manager Alex Neil said: "Jayden is going to Charlton to get some minutes which is good for him.
"I've said this about all the lads who aren't playing, I don't want them to sit here and for their careers to stall - I want them to go and play.
"Because someone goes elsewhere for some minutes for a period of time, it doesn't necessarily mean that when they come back their careers here are over.
"That is not the case. If they go elsewhere and do particularly well, who knows what might happen."
Charlton had tried to get Stockley earlier in the week in time to play against Peterborough on Tuesday night but hadn't manage to sort a deal.
He had a particularly good game against the Addicks last season, helping North End to a 1-0 win at The Valley in November 2019 which briefly took them top of the Championship.
Neil said: "Jayden needs to play. There have been a couple of times this season he was due to start and then for one reason or another, we couldn't play him.
"Had he been able to start those he would have got a bit more rhythm.
"He's been here for two years and needs to get some consistency in terms of match selection and I'm hoping he will get that at Charlton."
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