Sustainability Accounting is gradually gaining momentum, since then, awareness on environmental, economic and social issues in the business sector has increased mainly due to the increased pressure from stakeholders to ensure that their companies minimize their negative impact while maximizing on the positive effect of their operations and thus contributing to global sustainable development. The study was guided by the main objective, to establish the factors that influence the adoption of SMAT among companies in East Africa and the following objectives; to identify the level of application of sustainability management accounting tools among companies in East Africa and to identify the motivating factors that influence this level of application of sustainability management accounting tools in East Africa. The study followed a descriptive research design incorporating both qualitative and quantitative data in fulfilling the research objectives. A questionnaire was emailed to 119 respondents out of which 83 were duly submitted. The quantitative data collection tool was a questionnaire and the qualitative data collection tool used was observation methods and data analysis. The target population of the study will focus on forty four (44) companies in East Africa that have submitted their non-financial statements on the GRI website. From the study, application of the tools was found to be moderately low but each organization admitted to using at least one tool. Environmental tools were the most frequently used. Pressure to reduce costs, meet societal and stakeholders needs and develop and promote products that meet customers; demands accounted for the higher percentage of motivating factors. In conclusion, the study found a high correlation between application of Sustainability Management Tools in East Africa and motivating factors with legitimacy being the main factor of influence.