Founder Christian Arno hailed the arrival of Mr Gregory, who led oil and gas consultancy Wood Mackenzie for 19 years until 2007, as a major coup for the Edinburgh-based business.
Mr Gregory, who led a management buyout of Wood Mackenzie worth £20 million in 2001, has spearheaded a consortium of five investors to take a minority stake in Lingo24.
With the translation firm also securing an invoice finance facility from Lloyds, it plans to use the combined seven-figure injection to develop its proprietary translation software and boost its sales and marketing teams in Edinburgh and London.
Mr Arno said: "Paul Gregory is someone who has kept a low profile in the media but his achievements with Wood Mackenzie, in particular, are an absolute inspiration.
"To have someone like that dedicating proper thinking time to the challenges we face is priceless."
He added: "The other thing that's really useful is that he has got a different mindset to me, [he's] much more analytical. That will bring something that maybe we have not had in the past."
Lingo24, which provides services for clients such as Orange, Adidas and the United Nations in more than 50 countries, has grown turnover to £7.5m since its creation as a home-based start-up in 2001.
Mr Arno said he has no plans to float the company, noting he was "glad to be shot of" the distraction of raising finance which has occupied him in the last year.
However he added: "It certainly signifies a real level of ambition to be a much, much bigger business, and to grow much quicker than we have done in the last couple of years."
Asked how the new funding package will be deployed, Mr Arno said there would be further investment in its proprietary translation software, signalling his hope to grow more quickly on the technology side.
A particular focus will be on Translation API, which allows companies to link their content management systems with its translation platform.
Mr Arno noted that the firm carries out most of its software development in Romania, where it has had a hub for five years.
But he intends to open a machine translation centre of excellence in Edinburgh, where he hopes to tap into the "computational linguistics" developed by the University of Edinburgh.
He said the centre will result in a limited of new jobs being created in the city.
The firm will also the take steps to recruit account directors and marketing specialists.
Lingo 24 reported 12% growth last year, with 60% of its business originating outside the UK.
Mr Arno anticipates an acceleration of growth as the impact of the new investment is felt.
He added: "I think the real impact that all of the investment will make from now on will come next year.
"We're investing in different areas that will deliver faster growth in the months to come, rather than in the months to come.
"We had growth of 12% last year and I would predict we should easily beat that."
Mr Gregory said: "I've known Christian and Lingo24 for almost two years now, and the company has significantly strengthened the management team in that time.
He went on to outline his aim as chairman: "Lingo24 has built an impressive platform for future growth in a £23 billion global market, and I'm looking forward to getting closely involved to help the company achieve its potential."