It's the latest 24-hour strike in the past few months for the parcel delivery industry, which has seen companies and workers at loggerheads over work conditions and outsourcing.
Last week FedEx workers paused strikes planned for Thursday after the parties came close to securing an agreement.
But Transport Workers' Union National Secretary Michael Kaine said talks broke down on Thursday and FedEx declined requests to meet again on Friday to try to prevent Monday's strike.
"FedEx is determined to trample all over its workforce trying to achieve job security and parity with their counterparts across the industry," he said.
"Although FedEx raked in record profits above $US5 billion last year, it is going to great lengths to swindle workers out of an agreement which secures their future and allows them to catch up to other major transport operators like Toll and Linfox."
StarTrack workers went on strike on Thursday for the second time in a month.
Australians are already facing longer than usual wait times for parcel deliveries, with the sector buckling under the pressure caused by a spike in online shopping amid months of lockdown.
A FedEx spokeswoman said the strike could not come at a worse time for Australian businesses coming out of lockdown and customers would be adversely impacted.
The company had addressed the union's primary concern of job security and made concessions to resolve approximately 90 per cent of the union's claims, she said.
An industry-wide strike planned for last week was avoided after deals were reached at Toll, Linfox, Global Express and BevChain.
AAP with The Project