Gorham, who will have been chief executive for over seven years by the time he leaves, is to be replaced by chief financial officer Chris Hill, who will become deputy chief executive from 1 October this year.
In a separate statement from the results, the board thanked Gorham for his "outstanding contribution" to Hargreaves Lansdown, while Gorham said he had put his full energies into the business and shareholders and clients would be best served by "new zest" being applied going forward.
Net revenue for the group grew 11% to £326.5m ($436.7m, €388.3m) from £294.2m and active clients jumped by 100,000 in the year to 836,000.
But net new business inflows fell 2% in the year to £6.0bn from £6.1bn in the previous financial year.
Asset gathering continued despite low confidence
Gorham said: "The results demonstrated a healthy profit growth and continued substantial new assets and clients. Hargreaves Lansdown is well positioned to take advantage of the structural opportunity for growth in the savings and investments market, including the launch of the Lifetime Isa in April next year.”
Asset gathering had continued "despite periods of low investor confidence during the year, particularly in the first quarter of the current calendar year which had historically been a strong period for the company".
Investors have been concerned by weaker financial markets, geo-political uncertainty, economic weakness and, in the latter stages of the reporting period, the debate surrounding the referendum on the UK’s membership of the European Union, he said.
Looking ahead, he said by 30 June 2017 the company would launch its cash management service, HL Savings, which Gorham said would mark its entry into an asset sector of significant interest to clients – cash deposits – as well as peer-to-peer lending which will follow in 2017.
Expansion of the fund management range, growing its Portfolio+ service, and a new version of HL Live for iPhone and Android would also “launch in the coming year”.