Can a son married to a Singaporean immigrate?

Your first consideration is not whether your son can immigrate, but yourself.

You can apply for a green card (PR) for yourself within a few years after you marry a Singaporean.

You can apply for Singapore citizenship for yourself within two years after getting PR.

However, the nationality of PR is not necessarily approved, depending on your husband and your personal conditions. Mainly to see your husband.

If your son is under 2 1 year old when you successfully obtain Singapore citizenship, then you can guarantee to apply for Singapore citizenship for him. This is not necessarily approved, it depends on your own conditions (education, salary)

If you have any questions, ask them.