The 17-year-old made his Championship debut against Leeds United recently, replacing former Leyton Orient forward Josh Koroma.
Harratt signed a first professional deal with The Terries in November following a 2018/19 season that caught the eye.
The Yorkshire-born forward scored over 30 goals as he progressed from the U17s up to the U19s at The John Smith's Stadium, with First Team Manager Danny Cowley one of many admirers.
"He's really exciting, really exciting. We've had the pleasure of him training with us a couple of times and he's done great.” Cowley told Huddersfield's club website.
"He's a good kid with a real chance - it's only ever a chance - but certainly you look at his focus and his work ethic and the qualities that he brings, we're looking forward to seeing how he develops."
Harratt's performances that year earned him the accolade of Huddersfield Town Scholar of the Year, form that has shown no signs of slowing down, with Rochdale the latest recipients of Harratt's goalscoring touch, netting two on Thursday for Huddersfield's Academy.
Prior to his move to Huddersfield in Summer 2018, Harratt had spent time at Leeds and Barnsley as a youngster
Here's a glimpse of what our latest arrival is capable of…
Harratt has been given the number 28 shirt and will be available for Saturday's trip to Ebbslfeet.