The Irish company already trades across eight European markets and the deal will allow it to continue to scale its operations internationally.
Mitsubishi's market capitalisation is in excess of €32 billion and it is Japan’s largest trading and investment company.
ElectroRoute’s entire senior founding management team, including chief executive Ronan Doherty, will remain on as it moves ahead with plans to open its first offices outside of Ireland.
ElectroRoute has grown rapidly from a start-up of four people in 2011 to a workforce of over 40 today and a presence in energy markets in Ireland, Britain, Netherlands, France, Italy, Germany, and Spain.
It trades energy on a 24/7 basis across the entire spectrum with spot trading, futures trading, cross-border trading and green certificates trading.
It also provides managed trading services to energy assets, giving them ready access to pan-European markets.
ElectroRoute is the first company of its kind to be added to Mitsubishi Corporation’s portfolio.
Doherty said: “The interest in our company from a trading house with the scale and heritage of Mitsubishi Corporation is a wonderful validation of our business model.
"With their support, ElectroRoute is now ideally placed to strengthen our positioning within our international energy markets."
ElectroRoute was initially supported by Enterprise Ireland and The Bank of Ireland Start-Up and Emerging Sectors Equity Fund, managed by Delta Partners.
Meanwhile, the Irish-owned Americk Packaging has been acquired in full by Spanish multinational Saica.
The privately-owned manufacturer of flexible labels and carton packaging employs 691 people.
In 2015 it had a turnover of €120 million.
The business is located across six sites in Ireland and Britain.
Additional operations include PP Global and Starfish Brand Solutions which operate as independent brands.
Saica president Ramon Alejandro said “This agreement allows us to enter the flexible packaging market in Ireland and Britain more actively, hand in hand with a leading player."
Saica Group is the European leader in the development and production of recycled paper for corrugated cardboard with a 2.5 million tonnes capacity.
It has 8,000 employees across Spain, France, Italy, Portugal, Britain, Ireland, Turkey and Luxembourg,
The consolidated turnover of the business is €2,378 million.
The agreement is subject to approval from the Irish Competition and Consumer Protection Commission.