After a strong performance for many emerging markets since early 2016, as concerns over the economic outlook receded, investor sentiment has continued to improve, driving the rise in assets.
"Investors are increasingly focussing on Emerging Markets and it is encouraging to see strong inflows this quarter," said Chief Executive Mark Coombs said in a statement.
"Emerging Markets are continuing to outperform as we would expect at this point in the cycle, with perceived challenges such as rising U.S. interest rates having been anticipated and priced in."
Total assets at the end of September were $65 billion, up $6.3 billion from the prior quarter, after investors pumped $4.3 billion into its funds and market gains added a further $2.3 billion.
A reduction in Ashmore's equity interest in Taiping Fund Management Company during the period resulted in a reduction in assets of $300 million, it said.
"The results will most likely be taken positively by the market, but given where the valuation is, these numbers are necessary to justify the share price," said KBW analyst Jonathan Richards in a note to clients, calling the results a beat.
Strong investment performance meant Ashmore was "well positioned to speak to investors with underweight allocations to Emerging Markets", he added, flagging a 'market perform' rating and a 355 pence price target on the stock.
At 0733 GMT, shares in Ashmore were up around 10 percent, among the top gainers in the FTSE mid-cap index <.FTMC>.
(Reporting by Simon Jessop; Editing by Rachel Armstrong and Adrian Croft)
By Simon Jessop