Isio is set to acquire Premier Pensions for an undisclosed sum, subject to Financial Conduct Authority approval.
Isio - the former pensions advisory arm of KPMG - launched in March 2020 and said its expansion with the Premier Pensions acquisition will allow it to offer "a broader spectrum of pensions and financial advisory services".
The acquisition will expand Isio's pensions administration, actuarial consulting and investment advisory services to include employee benefits and wealth management.
Isio's workforce will comprise 800 members of staff across nine locations in the UK following the acquisition, with estimated annual revenues of around £100m.
"Our independence has given us the ability to spread our wings, not only to grow organically but with the support of our investors, to invest in our core business and to identify and take the opportunity to acquire a complementary business that will accelerate our growth trajectory," said Isio chief executive and partner Andrew Coles.
He added: "The UK's pensions industry is undergoing a significant revolution. Innovative thinking and new ways of managing employer pension responsibilities, employee benefits and individuals' wealth are required for the future of the UK's financial services industry.
"Acquiring Premier gives us the versatility to do this, by offering new and existing clients the full spectrum of employee benefits advice, actuarial consulting services, as well as wealth management and financial advisory and pension administration services."
Premier chief executive Alistair Aird said Isio was "very much aligned" to the Premier business, including the original proposition the company had been founded on.
"Together we see great opportunities to build a much stronger organisation," he said. "We look forward to working with the team at Isio to bring the two companies together and create a unique position in the market as an agile, fast paced and complete pension, employee benefit and wealth adviser able to service the whole of the market."