It is part of the State Government's $7 million project to replace lifts and escalators at Warwick, Joondalup, Whitfords, Stirling and Glendalough stations as well as some at Perth Station.
The new lift at Joondalup replaces the 20-year-old elevator and can cater for two large wheelchairs.
Transport Minister Dean Nalder thanked the community for its patience during the work.
"I accept the temporary closure of the lift created difficulty for some passengers," he said.
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READ NOW"This has been undertaken with the very best of intentions so that the lift is reliable in the long-term.
"A growing number of people rely on public transport and for passengers with accessibility challenges, our rail and bus systems are incredibly important. So we must ensure our facilities are accessible and operational."
To reduce the effect on passengers, the Joondalup project was shortened from four months to three.