Are Singapore Permanent Residents eligible for H1B1 visas as principal applicants?

No. Permanent residence in Singapore, however long held, does not open the H-1B1 to a principal applicant. Citizenship is the test, and the reason is worth following because it explains why there is no room for argument on the point.

INA 101(a)(15)(H)(i)(b1) does not name any country. It covers a person who is entitled to enter the United States under and in pursuance of an agreement listed in INA 214(g)(8)(A), which is to say the free trade agreement with Singapore or the one with Chile. The Singapore share of the annual numbers is then set aside at INA 214(g)(8)(B)(ii)(II) for nationals of Singapore as defined in Annex 1A of that agreement, and Annex 1A defines a national, with respect to Singapore, as any person who is a citizen within the meaning of its Constitution and domestic laws. The temporary entry chapter of the agreement points the same way: it defines a professional as a national of a Party engaged in a specialty occupation. Nationality in this scheme means citizenship, so a Singapore permanent resident who is a citizen of some other country falls outside the classification no matter where they live or work.

Family members are governed by a different rule, which is why permanent residents often appear in H-1B1 cases anyway. The spouse and children of an H-1B1 worker qualify for H-4 status on the strength of the principal’s classification, not their own nationality, and INA 214(g)(8)(B)(iii) confirms that the annual limits reach only principal applicants and not spouses or children. A Singapore permanent resident who holds another citizenship can therefore accompany a Singaporean H-1B1 spouse or parent in H-4 status.

For a permanent resident who needs to work in the United States in their own right, the H-1B1 is simply the wrong door. Two other possibilities are worth checking. The person’s actual citizenship may carry its own agreement-based category, such as H-1B1 for a Chilean national, E-3 for an Australian or TN for a Canadian or Mexican. Failing that, the ordinary H-1B is indifferent to nationality, though it comes with the general cap and the selection process that the H-1B1 avoids.