The announcement by the Liberty House came as the industrial group formally completed its acquisition of the Speciality Steels Business it bought from the Indian firm earlier this year.
The move also protects the jobs of 1,700 existing staff at five sites.
Liberty said it would invest £20m in the business in the first year to boost competitiveness and secure international market leadership.
Liberty House chief executive Sanjeev Gupta said: "We are casting a big vote of confidence in the future of British industry.
"With the right business model and an innovative approach, the UK steel and engineering sectors can recover and thrive.
"The Government is now pursuing a new post-Brexit industrial strategy and steel must be at the heart of that strategy."
The announcement comes as latest economic data shows the manufacturing sector expanded at its fastest pace in three years in April.
Liberty is buying a business which develops steels for use in vehicle, aircraft and industrial machinery making, and equipment for the oil and gas industry.
Its plans will raise output at its electric arc furnaces, casting shop and bar mill in Rotherham, with further expansion across the wider business expected in the years to come.
The speciality steels business also includes other sites in South Yorkshire, as well as in Bolton and at Wednesbury, in the West Midlands, plus two distribution centres in China.
Liberty's acquisition, which was confirmed earlier this year, makes it one of the largest steel and engineering employers in the UK, with more than 4,500 workers.
The UK steel sector is emerging from a crisis that saw thousands of jobs axed over the last couple of years as it buckled under pressure from cheap Chinese imports.