Real estate moguls Robert and Philip Ng have been ranked in the list with a net worth of $10.6 billion, followed by Kwek LengBeng & family with $7.1 billion in second position.
Forbes selected Modi after a evaluation based on a variety of considerations such as the overall performance, technological innovation and expertise in various fields, Spice Global said in a statement.
Modi became a Singapore citizen in January 2012 after moving headquarters of his $2 billion conglomerate to the island state. The Spice Global chief caused quite a stir when he mooted proposal that the Singapore government should lower the eligible age for public housing from 35 to 25 to encourage young people to procreate.
Seventy per cent of Modi's assets has been invested in real estate in cities including New York, London and the Southeast Asian island state and in various industries including telecommunications, healthcare, hospitality and financial services.