The 999 service revealed last week it was planning a temporary station on land previously occupied by Lunar Caravans.
"This is a great step forward and a significant investment in modernising our service and providing our staff with an effective, safe and comfortable working environment," said Neil Maher, assistant director of estates, fleet and facilities management at the North West Ambulance Service (NWAS).
The interim hub is necessary because crews will have to vacate their current home at the fire station in Blackpool Road in less than five months.
The two emergency services have shared the building since March 2014 when ambulance staff were forced out of their previous base in Deepdale Road because it was declared dangerous due to subsidence.
But the NWAS lease runs out at the end of September and Lancashire Fire and Rescue says it needs the space used by the paramedics for some of its non-operational teams who are moving in from other sites as part of a major redevelopment at the station.
As a temporary measure the ambulance staff will be housed in a modular building to be constructed on the new site off Sherdley Road, Lostock Hall, subject to planning approval.
Speculation that the land could eventually house a permanent base followed talks last year over a larger plan which included a training centre but was never submitted to the council.
Neil Maher explained: "The current lease arrangement held with Lancashire Fire and Rescue Service (LFRS) for the Blackpool Road station is due to expire on 30 September 2022.
“We have already purchased a development plot at Sherdley Road, Preston, where a new ambulance hub will be built.
“As an interim solution is required, planning permission for a modular structure to temporarily house our staff and vehicles has been submitted.
"We will be working through that process over the coming weeks to ensure we have alternative premises up and running before the 30th September.”
The plans to move to Lostock Hall will mean the bulk of Preston's ambulance crews will be based in the south of the city for the first time in decades.
Explaining the decision not to renew the NWAS lease, a fire brigade spokesman explained: "Lancashire Fire and Rescue Service has plans to develop the facilities on Blackpool Road and move some of our non-operational teams to the site.
"To facilitate these improvements and cost efficiencies, the service needs the space that North West Ambulance Service currently utilises and as such the lease will not be renewed.
"In 2020 Lancashire Fire and Rescue Service and North West Ambulance Service extended the agreement for sharing facilities at Preston Fire Station until 30 September 2022.
"Prior to this agreement, the service consulted with North West Ambulance Service on their future plans and they confirmed that a joint fire and ambulance station on this site did not fit with their strategy."
The temporary building in Lostock Hall will house up to 23 vehicles and 37 staff.