Over his 20-year journalism career, Matsui has focused on trauma and victimization, developing an ability for relational, intimate documentary work. His photojournalistic style, after years spent covering news, results in observational and visceral cinematography.

A non-profit founder, he combined documentary films with sexual violence advocacy work. After covering international human trafficking, he focused on domestic minor sex trafficking to produce The Long Night, a feature-length documentary. He reported, directed, and shot the film, and then, using his non-profit experience, created a grassroots impact campaign.

Through community and government partnership, Matsui co-created and co-hosted a convening with the King County (WA) Executive, Sheriff, and Prosecutor to develop regional policies on sex trafficking. His work is still in use nationally.

In 2015, Tim swept the photojournalism industry awards for The Long Night with first place prizes at World Press Photo, Pictures of the Year International, and Best of Photojournalism.

He was also recognized by the Overseas Press Club, and has won grants from the Open Society Foundations, Fledgling Fund, Alexia Foundation, and the Fund for Investigative Journalism. He has produced fundraising, communications, and impact campaigns with the Casey Family Programs, Drug Policy Alliance, Shultz Family Foundation, Starbucks, and YouthCare. He was nominated for two National News & Documentary Emmy Awards and was a finalist for both the Stanford-Knight Journalism Fellowship and the Guggenheim Fellowship.