The terms of the contract were not revealed.
Covalent Lithium is a joint venture between Wesfarmers and SQM.
Under the contract, Thiess will deliver drill and blast services, mining of overburden and ore, and equipment maintenance with a strong focus on community development and environmental protection.
"We are very pleased to be selected by Covalent to undertake mining at the Mount Holland mine," Thiess executive chairman and CEO Michael Wright said.
"This award recognises our team's ability to deliver sustainable mining solutions and deliver enduring value for our clients across diverse commodities.
"We look forward to working with Covalent Lithium to safely position their operations for optimal efficiency, productivity and cost performance, and contribute strongly to a clean energy future."
Thiess commenced mobilisation and early mining operations in January.
Covalent approved the A$1.9 billion project in February 2021.
