Home-based interventions targeting children's sedentary behaviours have had limited and inconsistent effectiveness, possibly due to a mismatch between the behaviours targeted, the behaviours actually performed, and health-risk messages parents need to initiate change. Between October 2017-February 2018, 540 parents completed an online survey indicating their own and their child's participation in 15 home-based sedentary behaviours (child mean age 11.1 ± 2.61 years, 52% male; parent mean age 40.7 ± 6.14, 93% female). Parents also indicated which home-based sedentary behaviours they and their child could reduce, and what health-risk messages would make them change their child's behaviours. The most prevalent sedentary behaviours among children (particularly older children) and parents were screen-based leisure-time activities, specifically TV/video/DVD use (67.5 and 62.5 min/day, respectively) and using a tablet/smart phone for leisure (53.6 and 80.8 min/day, respectively). Importantly, these were also perceived as the most feasible behaviours parents and children could reduce. Parents reported that the following messages would help them reduce their child's sedentary behaviour: sitting may increase the risk of poor mental health (85.2% of parents) and adversely impact future health as an adult (85.1%). These findings highlight feasible behavioural targets and intervention content for programs aiming to reduce sedentary behaviours in the home environment. Further research is needed to test these strategies.