Al-Musaileem became acting CEO of Tamam in August 2021 and CEO a year later in August 2022. Tamam is a Shariah compliant fintech that provides micro-financing services and loans. Al-Musaileem was a key member of the founding team from Zain Group that established Tamam in Saudi Arabia in 2019. As of September 2024, the company’s app had been downloaded over 3.4 million times, with more than $500 million disbursed between August 2021 and September 2024.