Issue AddressedSouth Asians make up the second‐largest group of immigrants in Australia and experience a higher burden of chronic diseases compared with non‐immigrants. Most chronic diseases are associated with insufficient physical activity (PA) and sedentary behaviour (SB); however, studies involving PA and SB in immigrants are limited. This study aimed to explore PA and SB and associated factors among South Asian immigrants in Australia.MethodsSouth Asian adult immigrants in Australia were surveyed online (from November 2020 to March 2021) about PA, SB, knowledge and barriers to PA. Logistic regressions were used to examine factors associated with insufficient PA (<150 minutes/week) and a high sitting time (>8 hours/day).ResultsA total of 321 participants provided complete data. Approximately 76% of participants reported insufficient PA and 27% reported high sitting time. Only 6% of participants walked or bicycled. The main reported barriers to PA were lack of time, costs, transport facilities, skills, and culturally appropriate resources. Around 52% of participants were not aware of the importance of PA. Participants with self‐reported poor health and who used motorized travel were more likely to have inadequate PA. High sitting time was more common among middle‐aged, overweight/obese, and middle‐income participants.ConclusionsMost South Asian immigrants are insufficiently active with a lack of socio‐economically appropriate PA facilities identified as a major challenge. A stronger collaboration between policymakers and community is required for sustainable solutions.So What?Affordable and appropriate PA facilities in neighbourhoods could overcome major barriers. Also, information about PA should incorporate cultural expectations in the general recommendations to encourage participation.