The syndicated facility, led by HSBC, has been increased to $200 million.
According to Macmahon the terms of the increased and extended facility has improved terms including a margin below the present senior facilities agreement.
The maturity date of the facility, which is available for equipment financing, working capital and general corporate purposes, has been extended by more than three years to September 2026.
Macmahon chief financial officer Ursula Lummis was pleased with the refinancing outcome.
"The successful refinancing and extension of Macmahon's debt facility on favourable terms demonstrates the continued confidence in the business from our banking syndicate," she said.
"The extended facility supports the company's strong liquidity position and provides funding flexibility as we invest in growth with a focus on cost effective and prudent capital management."