About £2.8bn of the total inflows came from Intrinsic, the financial adviser network bought out by OMW in 2014.
The figures pushed total funds under management (FUM) across the group up to £131.3bn by the end of September.
Paul Feeney, chief executive of Old Mutual Wealth, said: “NCCF as a proportion of opening funds under management, excluding Heritage, on an annualised basis of 11% is well ahead of our 5% target.
“In particular, the continued robustness and year-on-year growth of our integrated flows demonstrates the strength and value of our business model.”
The results show FUM at Quilter Cheviot, part of the OMW group, rose £2.3bn on the previous year after net flows hit £1bn and market movements pushed up the value by £1.3bn.
Within Old Mutual Global Investors (OMGI), single strategy funds saw the biggest net flows, £1.2bn more than its multi-asset strategies.
“While market conditions have remained relatively buoyant so far in 2017, we anticipate continued uncertainties in equity, bond and currency markets in the medium term as the potential impacts of the UK’s exit from the EU evolve over the next two years,” Feeney added.
He said the company was “encouraged by the opportunities ahead” as it prepared to list on the stock exchange in 2018 – part of the so-called ‘managed separation’ of the Old Mutual brand.
OMW is set to split from the Richard Buxton-led OMGI arm next year, the news of which has sparked a bidding war for the asset management firm.
OMGI is due to be split and the £16bn multi-asset business separated from the single-strategy funds.
Buxton is reported to be looking for private equity to back his bid for the single strategy arm, and two Australian firms, Challenger and Macquarie, were recently reported to have entered the race to bid for the £25bn business.