The deal ensured Glencore would provide a minimum 61,200 tonnes of cobalt to GEM between 2020 and 2024, the equivalent of roughly one year's production at current rates.
China has led the strategic procurement of minerals for decades and is acutely reliant on cobalt - two thirds of which comes from the politically precarious DRC - for its energy transition.
The pair came close to an agreement a year ago, but market volatility at the time stymied alignment on pricing. The LME-traded cobalt price was more than US$60,000 per tonne in October 2018 but has since fallen back to around $35,000/t and steadied around those levels.
GEM chairman Kaihua Xu said the contract represented a "cornerstone" in the group's "cobalt-sourcing strategy".
"By securing a key battery raw material, GEM clearly demonstrates its ability to implement and deliver its vision for an electrified, carbon-free transportation system," he said.
"GEM will continue focusing on the development and the manufacturing of high-quality sustainable cobalt products to meet the fast-growing demand for cobalt-containing battery products."
Glencore copper-cobalt marketing chief Nico Paraskevas said the deal provided a "stable outlet for a significant portion of … future cobalt hydroxide production".