Zakat is a powerful source of good with untapped potential for contributing to sustainable development. There are some striking commonalities between the sustainable development goals (SDGs) and zakat. Zakat is mandatory giving; all Muslims eligible to pay it must donate at least 2.5% of their accumulated wealth for the benefit of the poor. But despite its tremendous potential for contributing to the SDGs, zakat organisations have been overlooked by development organisations. Between $3tn and $5tn is estimated to be needed per year to achieve the goals, but current investment falls short at around $1.4tn. By working together with religious organisations, development bodies can fill the $2.5tn investment gap, while also promoting peace and development. A shift in the public mindset is needed so that zakat is seen as a programme needing professional management for positive change, rather than simply charity.