In his role as CEO and partner at Mandelbaum Barrett PC, William Barrett has built his success on old-school values. Even as many young leaders question these principles, Barrett is determined to prove their enduring relevance through mentorship and personal growth. With those foundations, he aims to help entrepreneurs build and scale businesses for the long term.
Building a Meaningful Career
Like so many before him, Barrett was drawn to pursue a career in law and join a prestigious global law firm. Through dedication, he achieved this goal; once there, however, he realized that what he valued most was the chance to work directly with entrepreneurs and play a meaningful role in their journeys.
“Early in my career, I realized that what energized me most wasn’t the work itself, but the impact it could have,” Barrett said. “My role gave me a platform to support people in ways that could change the trajectory of their professional lives.”
Recognizing this passion, Barrett found a home in a smaller regional firm where he could build a practice centered on clients. It wasn’t the most obvious path, but it offered the chance to work hard, lead with integrity, and build genuine relationships—tenets of the old-school values he believes in. Today, Mandelbaum Barrett PC reflects that philosophy, grounded in relationships that create real impact.
Extending Impact to Others
Over time, making an impact on others became the throughline of Barrett’s work. His role at Mandelbaum Barrett PC gave him a platform to support clients, and he carried that instinct beyond the firm as well. He began coaching youth sports, serving on his town council, and stepping into mentoring roles whenever possible.
“Getting involved in this profession was really an extension of that impulse,” Barrett explained, “to be a hero to as many people as I could.”
Over the course of his career, Barrett has guided more than a thousand entrepreneurs through some of their most important business decisions. Grounded in trust, strategy, and authenticity, his mentorship and guidance have contributed to meaningful growth across industries. As such, Barrett was named among the Best Lawyers in America in corporate law in 2025 and to the New Jersey Super Lawyers list in 2026.
Creative Contributions
Beyond his efforts at Mandelbaum Barrett , Barrett has extended his mentorship efforts through creative contributions. As the host of the Fingerprints on Success business and entrepreneurship podcast, he helps listeners navigate the entrepreneurial journey with greater confidence.
Barrett has also authored multiple books, including The DSO Decision and Pain Free Dental Deals, each aimed at helping practice owners make confident, well-informed decisions during complex, high-stakes transitions. His latest book, Authentic: An Old-School Approach to Building a Full Life, Successful Business, and Real Relationships, focuses on how to make a strong impact while outworking everyone without losing what matters most.
Future Ambition
Moving forward, Barrett intends to continue in his mission of mentorship and professional growth. He believes that everyone should be empowered to strive for a bigger, brighter future in both their relationships and careers. Personally, Barrett aims to scale up Mandelbaum Barrett PC, thereby creating more opportunities for entrepreneurs to bring their creations to market.
“To me,” Barrett concluded, “that would be what success looks like. Strategically looking for additional opportunities across the country, and expanding the presence and influence of our firm.”
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