The funding comes as the Glasgow-based firm, which manufactures adapted and special purpose vehicles such as taxis and wheelchair-accessible cars, targets growth of 10% this year.
Allied's confidence in future trading follows two major developments at the firm last year.
The company, which booked a pre-tax profit of £1m in the year to April, opened a first Mobility Solutions store, on Glasgow's Hawthorn Street, in 2013.
It also landed a major contract with Motability Operations, the not-for-profit organisation which provides cars for disabled people.
Allied's 8000 square foot outlet is stocked with a wide range of mobility equipment and daily living aids. These include scooters, wheelchairs, specialist beds, rise and recline chairs, walking aids, kitchen and bathroom accessories, stair lifts and accessible vehicles.
The store is already said to have developed a strong client base.
The deal with Motability means Allied will be the sole supplier of replacement accessible vehicles to the organisation until February 2016. Motability, which offers customers suitable and affordable cars through contract hire, is committed to providing replacements when cars are off the road.
Through its Mobility division, Allied, which saw turnover across the group rise by 11% to £73.3m last year, is already the UK's largest wheelchair-accessible vehicle manufacturer.
The group has upped its headcount by 63 to 438 in the last two years after witnessing sustained growth, with turnover reaching £65.8m in 2012, up 19% on 2008.
Paul Nelson, managing director of Allied Vehicles, said: "2013 has been a bumper year for Allied Vehicles with the Motability contract and the new superstore opening.
"Our increased funding has allowed us to take on new work and we hope to see our business expansion continue to develop and grow.
"The superstore has proven to be a great success and if revenues were to continue like this, we would hope to roll out further stores in due course."
Mark Hull, relationship director at Bank of Scotland, said: "It is encouraging to see Allied Vehicles diversifying and expanding its business offering and it is important to Bank of Scotland that we can help provide the means to support this growth.
"We are witnessing positive signs of change and renewed confidence in the market and Allied Vehicles provides a great reflection of this."