The 21-year-old spent the first half of the season on loan with League Two Morecambe, amassing 25 games.
The Newcastle United youngster then moved to the Proact for the second half of the season and sufficiently impressed Chesterfield manager John Sheridan to earn a permanent move this summer after his Magpies release.
Yarney signed a two-year contract with the Spireites yesterday.
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READ: Chesterfield sign experienced defender and three of last season's SpireitesAlthough 2018 did bring some valuable game time in Newcastle's pre-season friendlies, the opportunities he had in competitive senior football give him belief that he's become a better player.
"The player I am now, to where I was this time last year, I've improved massively and learned a lot as well," said the defender.
Yarney could previously only call upon his experience of the EFL Trophy, at both Everton at Newcastle.
But with League Two and National League games on the CV, he's now got a taste for regular football in the men's game.
"I had to go out on loan spells and I don't really want to go back to playing Under 23s, I want to be playing in the men's game," he said.
"It's about competing every game.
"Maybe sometimes if you're playing Under 23s some games might be hard, some might be easy.
"When you're playing in the men's game every game is hard, you have to compete in every single game."
His stint as a temporary Spireite yielded 15 appearances and he relished the chance to work under Sheridan, who he feels will continue to develop his talent.
"I felt good last year, I enjoyed playing here, the manager made me feel welcome and I enjoyed it.
"He's good. He's a good manager. He's been a top player in his time.
"He lets me play my game and he's going to improve me as a player."
Yarney featured at right wing-back and centre-half, as part of a back three, while on loan at the Proact last season.
Sheridan is yet to give an indication of the system he'll use in the 2019/20 campaign, or where he sees Yarney's future.
What is known is that the manager is determined to get his Spireites playing attractive football and that suits the new boy.
"Since I was a kid I've always been good on the ball and taught to be on the ball.
"John likes to play like that so it's good."