The 17-year-old midfielder will get his first chance to shine in first-team football at Oakwell, after previously being compared to Jack Wilshere.
The 17-year-old has been lauded as one of the brightest prospects at the Emirates, with the likes of the Mail comparing his playing style, physique and potential to England international Jack Wilshere.
The England Under-17 star was part of the club's Singapore tour this summer after captaining the Arsenal FA Youth Cup side last season.
Like Crowley, Wilshere was a star in the Gunners' youth teams before he first appeared in the first team at 16-years-old, going on to become a homegrown hero for Arsenal despite injury problems impacting his career. Many supporters would point to Wilshere's loan at Bolton Wanderers for the latter part of the 2009-10 season as the time when the midfielder proved he was ready for a regular role in Arsene Wenger's side.
Crowley joined from Aston Villa in 2013, where he had impressed in the youth teams, and will be hoping to benefit in a similar way to Wilshere in his loan spell at the Tykes, who are looking to bounce back into the Championship after spending a year out of the division following their relegation in 2014.
Manager Lee Johnson will have three young loan stars at the club this season, with Manchester United duo Joe Rothwell and Ben Pearson joining Crowley at Oakwell.