Lynzi Armstrong is a critical criminologist whose research has a socio-legal focus, concerned with how laws impact marginalised populations - particularly sex workers. Her primary research interest is sex workers' rights, examining the implications of laws and policies from the perspective of those directly impacted. Stigma, discrimination, injustice, and power are key themes of her work in this area. As an activist scholar, she seeks to dispel myths and stereotypes through her research, foregrounding the voices of sex workers. In 2018 she was awarded a three year Marsden Fast Start grant to complete an international comparative project on stigma and sex work laws in New Zealand, Scotland and Ireland.

While sex work is her primary research interest, as a feminist criminologist her research and teaching interests also include diverse topics relating to gender and crime, and sexual violence, and she worked in related policy and practice roles prior to commencing her career as an academic.

Her work has been recognised for its novelty through publication in several academic journals and books, and she has delivered invited talks on it both locally and internationally. In 2018 she was the recipient of one of five Early Career Research Excellence Awards awarded by Victoria University of Wellington in recognition of the quality and impact of her work.

Lynzi regularly serves as an expert reviewer in her field, and she has reviewed grant proposals for funding bodies such as the Wellcome Trust, and articles for multiple academic journals and book publishers. She is currently an editorial board member of the the International Journal for Crime, Justice and Social Democracy, and Feminist Anthropology.