The company has been awarded a variation of an existing contract with Rio Tinto for the supply and installation of a new iron ore car dumper at Cape Lambert Port B.
The work will begin immediately for completion in the first half of next year.
The Monadelphous Muhibbah marine joint venture has also secured a contract with Wiggins Island coal export terminal for the construction and commissioning of a shiploader at Gladstone, which followed on from the contract for the construction of the approach jetty and ship berth for the project currently underway.
The additional work will be completed in the first quarter of 2014.
WICET also awarded Monadelphous a contract for the supply of fabricated steelwork and mechanical components for the stacker bridges and runway support gantries as part of the coal stockyard, which is set to be completed by the March quarter of next year.
New maintenance work includes a three-year contract for Woodside Energy on the Pluto LNG project, which includes work associated with its onshore and offshore facilities.
The contract has the option for two one-year extensions and builds on the construction and commissioning work Monadelphous has provided to the project since 2009.
Chevron also awarded the company a one-year extension to the general maintenance and services contract for the Barrow Island and Thevenard Island LNG operations.
The new work takes the value of new work secured by Monadelphous in the 2012 financial year to around $1.8 billion.
The company posted a record half-year profit of $57.5 million for the six months to December 31, 2011.
Monadelphous gained 11c to $24.20 in early trade.