With an increasing emphasis on sustainable planning, highway decision makers need to shift their focus from developing a cost-effective highway program to developing a more comprehensive sustainable highway program. It includes incorporating the three components of sustainability, namely economics, the environment, and social equity. Studies in the literature have primarily focused on economic and environmental objectives. However, there are limited studies incorporating social equity in highway maintenance and rehabilitation (M&R) programming. Additionally, a review of the existing literature indicated that although studies have focused on single or dual objectives of sustainability, the existing literature failed to address all the three components of sustainability simultaneously. Accordingly, this study aimed to address this issue by proposing an M&R budget allocation model for developing a sustainable highway asset management plan that concurrently focuses on all the three objectives of sustainability. The proposed model assists decision makers with a range of potential decision alternatives that address multiple sustainability objectives. The proposed model was applied to a case-study example on a road network in Texas. The findings from the case study indicated that decision makers can implement sustainable M&R programs that can efficiently achieve social equity objectives without specifically compromising the environmental and economic objectives.