The contract extends the existing umbrella contract at Anglo American's Moranbah North and Grosvenor mines and started on November 15.
Anglo American has the option to extend the term for an additional two years.
Work under this contract is estimated to contribute revenues of about A$250-$300 million over the three-year term.
The revenue and earnings from this contract extension have been included in the company's current FY2020 guidance.
The scope of work includes design, supply and installation, recovery and maintenance of ventilation structures and devices, as well as installation of secondary support.
It also includes outbye support and maintenance activities; conveyor belt installations and recovery; and development services.
Mastermyne CEO Tony Caruso said the company had a 17-year relationship with Anglo American.
"Moranbah North and Grosvenor mines supply high grade metallurgical coal to the international market for steel production, and we are pleased to support their successful operation," he said.
"The continuation of this contract reinforces Mastermyne's strong standing and value proposition in the sector and demonstrates the robust outlook for metallurgical coal."
Mastermyne shares fell 1% to $1.02, valuing the company at $103.7 million.