The founding partner of Penoyre and Prasad saw off competition from challengers Valerie Owen and notorious BNP member Peter Phillips.
Prasad will ascend to the big office in Portland Place in 12 months' time, at the end of Pringle's reign.
It is understood that Phillips was knocked out in the first round and then Prasad won on second transferable votes.
Phillips is believed to have picked up 1,400 votes in the ballot, although it is unclear how many of these were cast before his political affiliations became public.
Prasad stood on this manifesto:
an influential profession that will anticipate and respond to change; not be compromised by it;
effective campaigning for architecture to be at the heart of creating the places and buildings that society needs;
a younger, more diverse RIBA;
tackling climate change with full commitment, working with others, helping each architect to know what to do;
championing and expanding international membership, e.g. through the formation of well-supported international chapters;
strengthening the place of architecture in cultural life and the arts, through the RIBA Trust; and
championing members' interests while harnessing their insights, energies and will to achieve the above.
Speaking after the announcement this morning (26 July), Prasad said: 'I feel honoured and privileged to be elected to the next RIBA president and keenly conscious of the responsibility to make the changes set out in my manifesto.
'I want to thank warmly all those who supported me, and also Valerie Owen, whose own tremendous campaign ensured that the full range of issues was discussed.
'I look forward to supporting current president Jack Pringle over the next year and will make it a priority during this time to get closer to RIBA members, visiting as many as possible.
'We can only build the influential profession we want, and society needs, by the RIBA more effectively involving its members.
'As president I will have two other priorities. One will be campaigning for design because of the enormous difference it can make to people's lives.
'The other will be tackling the issue of climate change. Buildings account for 50 per cent of energy use - as a body of architects, the RIBA must play a key part in countering this threat to our collective futures,' he added.
And Owen, who came an extremely close second, offered her warm congratulations.
'I stood for president because I couldn't think of a better platform than mine to promote sustainable development,' she said.
'I feel this is a missed opportunity, but I do wish Sunand well for the future,' she added.