Masterlease has more than 100,000 cars and vans on its books and appointed Kwik-Fit on January 1.
Mike Wise, head of Kwik-Fit Fleet, said: "Securing a solus contract with Masterlease builds on our long-standing relationship with the company as one of its fast-fit suppliers."
A factor that helped Kwik-Fit Fleet clinch the new contract was its four UK training academies where apprentices, fitters and specialist technicians undertake courses.
Earlier this year Masterlease staff visited the Derby training academy for the first time to look at the training undertaken by Kwik-Fit’s centre fitters and mobile technicians.
Tim McNicholas, senior contracts manager at Masterlease, said: "Behind the well-known Kwik-Fit brand is a very professional academy powered by millions of pounds worth of investment in high-quality technical training.
"Having the opportunity to see this Academy in action gave the team at Masterlease further confidence in the working relationship we have with Kwik-Fit in the provision of fast-fit operations to our 100,000-strong fleet."