Which master's specialisation suits a graduate in Architecture applying to Singapore or Malaysia with 4 years of work experience?

Four years of architecture practice is real professional capital, and the strongest master's choice is one that adds a specialisation on top of that experience rather than repeating the same generalist architecture degree you already hold.

Why Sustainable Design Beats a Repeat Master of Architecture

The National University of Singapore's MSc in Integrated Sustainable Design is explicitly a post-professional programme integrating architecture, engineering, landscape and urban design at both building and city scale, and it treats professional experience as a genuine asset rather than a formality. For an architect with 4 years of practice, this adds a high-value specialisation such as sustainability consulting or net-zero design on top of existing design skills, rather than starting again at the same generalist level.

Urban Design as the Alternative if Your Four Years Were Masterplan Heavy

If your 4 years involved large developments, masterplans or mixed-use projects rather than individual buildings, NUS's Master of Urban Design or Master of Urban Planning, both of which list architecture as an eligible and favourably considered background, may suit you even better than sustainable design.

My Advice

What you actually did during your 4 years matters more than the fact that you are an architect. Someone who spent that time on BIM coordination and large-scale projects has a very different optimal specialisation from someone who spent it on residential interiors, so be specific about that in your application.