As a fifth-generation heir of the Lamsam family business, Nualphan Lamsam has held the positions of managing director and CEO at Muang Thai Insurance since 2014. Her brother, Sara Lamsam, serves as CEO and president of Muang Thai Life Assurance. Their father, Pothipong, is chairman.

Nualphan Lamsam sits on the board of a number of companies, including Saint-Honoré (Bangkok) Co Ltd, the Thailand importer of Hermès, which she founded in 1997.

In addition to her corporate responsibilities, she is also the manager of the Thai national football team. Nicknamed “Madam Pang” by Thai media, she has managed both the women's and men's football teams, and was manager of the Thailand national women’s team which made history when they earned a place at the 2015 FIFA Women's World Cup, appearing again in 2019. Lamsam took over Thai League 1 side Port and helped lead them to the FA Cup title in 2019. In August 2021 she was appointed manager of the Thailand national men's football team.