The Glasgow company, which spun-out from Strathclyde University in 2010 with £150,000 in seed funding, makes small lighting sources.
These solid-state optical micro-projection systems have applications in sectors including printing, communications, medicine and life sciences.
The firm plans to add two technical staff immediately, to bring its workforce to six, and hopes to have 12 employees within the next few months.
On top of that it is working towards raising a further £2 million towards the end of 2012 and has been working with London-based corporate finance house Duet Partners.
That money would be used to increase the workforce to more than 20 in 2013.
Professor Nick Kuenssberg, chairman of mLED, confirmed there was serious interest from "blue-chip" customers in the automotive, mobile internet device, data scanning and medical spheres.
He said: "We have got customers who are prepared to spend money with us in order to develop prototypes which should lead to commercialisation of the product. They have bought demonstrator kit from us and, based on that, understand what our technology can potentially do for them. We haven't got enough arms and legs at the moment so need to add people at a fairly rapid rate."
Braveheart Investment Group led the latest funding round with further support from the Scottish Co-Investment Fund and members of mLED's board and technical advisory council.