Deliveries will be spread across the company's nationwide network of rental branches and follows hot on the heels of £4m of new vehicles last year.
Orders for phases one and two have already been placed, totalling 216 vehicles split between Iveco and Mercedes-Benz, with deliveries commencing immediately.
The new vehicles range from 35- to 26-tonners and include vans, refrigerated vans, refrigerated boxes, boxes, curtainsiders, Lutons and dropsides.
Fraikin expects to finalise phase three this month, with the latest orders likely to total more than £4 million and a further 100 new vehicles.
"We're seeing a huge uplift in rental demand across the country, and particularly in the South East," says Mark Newnes, Fraikin's operations director.
"People have long said the rental sector is a good barometer for British business; if that's true then the signs are very encouraging."
This latest investment marks a strategic shift by Fraikin to grow the share of 3.5-tonne light commercials within its hire fleet.
Once all deliveries have been completed, almost one quarter of the company's rental fleet will be light commercial vehicles – up from 10% a year ago.
Fraikin is also heavily investing in the 12-tonne sector, in response to growing demand from customers keen to increase payload capacity over traditional 7.5-tonne rigid trucks.