The Australian International School has started construction on a new facility that will be able to accommodate 2,000 pupils aged between 18 months and six years old.
It currently has more than 450 pupils aged between two and six.
The new 50,000 sq m facility - an addition to its 39,451 sq m Lorong Chuan compound - will be ready in 2017.
The new area will have purpose-built facilities such as a 22m-long swimming pool and gymnasium for the children.
The extension is part of a $200 million investment by Cognita, which runs the Australian International School and Stamford American International School here.
This is mainly "to meet the demand in the grade levels where we don't have capacity", said Mr Brian Rogove, Asia-Pacific chief executive of Cognita.
The Australian school has seen wait lists for its early-years and elementary programmes, prompting the opening of its junior school in 2008 and its nursery programme in October last year.
It will expand classes to those aged 18 months with its extension.
The German European School Singapore takes in pupils from 18 months for parent-child groups, conducted in preparation for kindergarten. Most other international schools here take in pupils from around two years old.
Mr Rogove said: "A lot more parents now are really starting to feel that if they embark on their children's education at an earlier age, that will benefit their kids much later in life."
He said that the new facilities will be purpose-built for very young pupils as they have different needs from older ones. The facilities aim to enhance their perceptual-motor development, or ability to interact with the environment.
These are aimed at complementing an improved curriculum, including daily Mandarin and literacy lessons, a speech and drama programme, and weekly violin lessons.
Australian International School principal Andre Casson explained that engaging in various non-academic activities such as music programmes helps with students' academic results eventually.
"It's about educating the whole child, and laying down these important synapses that will ensure success later on in school," he added.
For Ms Louise Honner, 38, starting her children's education early, at a school that shares her teaching philosophy, is important.
She enrolled her two-year-old daughter, Josephine, in a full-time, play-based nursery in Norway when the girl was 17 months old.
Ms Honner was keen to keep her daughter in a "similar, developmentally appropriate setting", rather than a more academic one when the family moved to Singapore in January for her husband's work.
Now, Josephine is on the Australian International School's early-years programme. Ms Honner intends to enrol her four-month-old son in it when he turns 18 months.