The 21-year-old joins Derbyshire on a rookie contract for the 2020 season, with the club acting quickly to secure the paceman’s services after monitoring his progress throughout the winter.
Aitchison, who recorded best figures of 4-18 in eight Minor Counties Championship fixtures for Cheshire last season, most recently claimed 26 wickets in 11 matches for Parramatta District Cricket Club in New South Wales.
The previous winter he took 47 wickets in 17 matches at an average of 12.23 in Australia First Grade cricket for Macquarie University Cricket Club in Sydney.
The tall right-arm quick joined up with Derbyshire for pre-season training at Repton School in July and is available for selection in all formats in 2020.
Head of Cricket, Dave Houghton, said: “Ben is someone we were keen to take a look at, and he’s impressed us with his work ethic and quality in training.
“We’ve seen great progression from our young bowlers working with Steve Kirby, and Ben has integrated into that group really well.
“He’s another promising young talent and at just 21, it’s important we bring him in now and give him the opportunities to show us what he can do.”
Aitchison added: “I’m really pleased with the opportunity to join Derbyshire and be a part of a really exciting team.
“The coaches have been brilliant with me so far, and I feel really confident that working with them will help me keep getting better as a bowler.
“We have a lot of players looking to nail down a first team spot, and with the hectic schedule coming, I want to take any chances I’m given.”