Rabbi Hyamson founded the Board of Milah in New York in 1914, which grew to encompass Mohel certification, conferences on circumcision, and published studies.

He helped in the founding of a local Hebrew school and the formation of the Central Relief Committee of the Agudas HaRabbanim, which provided European yeshivas with much needed assistance.

He helped prevent the legislation of Calendar Reform, which on an international level would have created a "wandering" Sabbath, changing to a different day of the week each year.

Notwithstanding his formidably Orthodox credentials, Rabbi Hyamson was appointed Professor Emeritus of Codes at the Jewish Theological Seminary of America in 1915, serving until 1940.

Rabbi Hyamson translated Duties of the Heart, Books I (and II posthumously) of Maimonides's Mishneh Torah, and "Collatio Mosaicarum et Romanarum Legum".