Phuntsog Namgyal II (Sikkimese: ཕུན་ཚོག་རྣམ་རྒྱལ་; Wylie: phun tshog rnam rgyal) was the fifth Chogyal (king) of Sikkim.

[1] Early in his reign, a powerful Bhutia minister named Tamding attempted to overthrow the Chogyal, declaring himself king in opposition in 1738.

Tibet dispatched Rabden Sharpa as a regent in 1747 to help restore order.

Rabden also introduced the Mangsher Convention, Sikkim's first constitution, defining the powers and responsibilities of Sikkimese government bodies.

[2] In 1770, the same year the Chogyal died, there was a brief attempt at an invasion by Bhutan, but it was soon repelled by the Sikkimese.