The work forms part of Rio’s electrical infrastructure replacement program, carried out at Cape Lambert and East Intercourse Island.
It includes the replacement and refurbishment of electrical equipment, and follows SCEE’s completion of phase one works.
SCEE said the work would be completed by its services division over 12 months, starting immediately.
The new contract is the latest in a spate of Rio work SCEE has won over the past few months.
In February the company won a $40 million contract for further electrical and instrumentation work at Rio’s Cape Lambert Port B project in the Pilbara.
In January it also picked up a $10 million contract for electrical and instrumentation work at the Nammuldi mine in the Pilbara.
SCEE shares were last trading 1.2% higher at 77c.