Chief executive Stephen Goodman had previously said the group was interested in the press, and has now confirmed a deal has been sealed.
He told PrintWeek: "I am pleased to confirm we have signed contracts with Goss and will be acquiring the 64pp M5000 short-grain press, which will be installed at our YM Chantry facility.
"The commissioning date for the press requires firming up, but we expect this will be during December 2016," he said.
The terms of the deal were not disclosed.
The buy will take the number of short-grain presses across YM's four print sites to five.
"We're very pleased with the strong position we have in short-grain," Goodman added.
"We're busy across the short-grain presses in the group and this will support our business in that area. The new press will be used for a combination of publications work that we're discussing with people at the moment, and growth in in our commercial work."
There is room at Chantry's Wakefield site to install the press without changing the existing set-up. Installing the 64pp will involve extending an existing press base and some "minor alterations" Goodman said.
"Sales and production activity levels [at Chantry] continue to improve and the necessary re-equipping of the site remains on plan, with the first of the two Ferag stitching lines now fully operational; we expect the second Ferag stitching line to be operational later this month."
Chantry has five existing web presses, although one of those, an old eight-unit 16/32pp press is effectively mothballed. YM Group acquired Chantry from Polestar's administrators in a £2m deal in June.
PrintWeek understands that Goss International is selling the three nearly new M5000 presses at Sheffield on behalf of Shanghai Electric, the former owner of Goss, which arranged the finance for Polestar's original investment in three huge web presses.
Shanghai Electric Europa Leasing and Standard Chartered Bank (China) had a $25.5m (£19m) charge on the accounts of Polestar UK Print relating to the deal.
There has been speculation that an unnamed German printer is interested in the two 96pp webs from the site, while France's Groupe Maury Imprimatur has also been mooted as a possible buyer.
Maury was unavailable for comment at the time of writing, while Goss declined to comment.
PrintWeek also understands that the owner of the giant Sheffield supersite wants the building cleared by the end of the year, and will scrap any remaining equipment at that point. Access to the site is now tightly controlled, with a 24/7 security checkpoint in operation.
