Around 230 of the roles are across Aberdeen and Montrose with the remainder in Norway.
Grimsby-based Cosalt announced yesterday it intended to appoint administrators and it had agreed to sell its offshore arm to NBGI for an undisclosed sum.
NBGI is a major investor in Aberdeen-based oil and gas tool rental business ATR while Cobalt Offshore adds capacity in testing, safety services, inspection and lifting.
ATR's chief executive, Keith Moorhouse will lead the enlarged group, although both companies will continue to trade under their own names for the time being.
He said: "This deal will be welcomed by Cosalt's staff, customers and suppliers as an end to a period of uncertainty.
"Cosalt has an excellent technical and operational reputation and is an integral part of the supply chain of many of the energy sector's leading oil service companies and operators."
Between them, ATR and Cosalt will employ about 400 people and have combined revenue of £55 million.
NBGI hopes to grow the group to in excess of £100m in annual revenue and believes the Cosalt acquisition will open up opportunities for ATR in the Norwegian market.
Shares in Cosalt, the family business of Carphone Warehouse founder David Ross, have been suspended since May last year.
Recently it warned administration was a possibility unless it could persuade lenders, including RBS and HSBC, to extend facilities or find alternative sources of funding.
Cosalt yesterday warned the disposal of its assets by administrators was unlikely to result in shareholders receiving any value from their holdings.