Background: There is limited longitudinal evidence supporting a link between food outlet locations and dietary outcomes to inform policy and urban planning. This study examined how longitudinal changes in the local food environment within new residential developments influenced changes in adult dietary intake. Methods: Adult participant data (n = 3223 person-observations) were sourced from the RESIDential Environments (RESIDE) project across three time points between 2004 to 2012 in Perth, Western Australia. Fixed effects regression estimated the relationship between change in spatial exposure to the local food environment, individual behaviours and perceptions of the local food environment with dietary outcome variables (healthy diet score, unhealthy diet score, diet quality score and fruit/vegetable intake). Results: An increase over time in the percentage of healthy food outlets around the home was significantly (p ≤ 0.05) associated with an increase in healthy diet scores and an increase in the distance from home to the nearest café restaurant was significantly (p ≤ 0.05) associated with an increase in diet quality scores. Conclusions: Modifying the local food environment by increasing the relative proportion of healthy food outlets around the home may support healthier dietary intake.