Mary Cossey

Mary Cossey is a premier real estate professional known for her discerning eye, uncompromising standards, and commitment to delivering an elevated client experience. With an approach defined by precision, discretion, and personalized service, Mary has become a trusted name among discerning buyers and sellers seeking a sophisticated real estate experience.

Her exceptional results and dedication have positioned her among the industry’s elite. Mary is a two-time recipient of the International Diamond Society Award (2024 and 2025), ranking her among the top agents globally. She has also been honored as one of the Top 100 Agents by both the National Association of Real Estate Brokers (NAREB) and the Northwest Indiana Realtors Association (NIRA), a testament to her leadership and excellence in the field.

Specializing in the distinguished communities of Lake County—including St. John, Crown Point, Dyer, Merrillville, Hammond, and her hometown of Gary—Mary offers clients unparalleled market insight and a deep understanding of the area’s evolving luxury landscape. Her background in public utility and municipal governance further enhances her strategic advantage, allowing her to navigate complex transactions with ease and sophistication.

After earning her real estate license in 2011, Mary transitioned to full-time real estate in 2020, quickly becoming known for her integrity, negotiation skills, and client-centered approach. “Real estate isn’t just a career—it’s a calling,” she says. “There’s nothing more rewarding than matching a client with the perfect home or ensuring their property achieves its highest market potential.”

Mary’s business is built on enduring relationships. Clients describe her as honest, tireless, and deeply protective of their interests. Whether advocating through negotiations or coordinating luxury-level marketing strategies, her focus remains the same: curated service, unmatched attention to detail, and long-term satisfaction.

Beyond real estate, Mary is deeply involved in community leadership and service. She has held executive roles with the Gary Alumnae Chapter of Delta Sigma Theta Sorority, Inc., the Northern Indiana Chapter of The Links, Incorporated, and the Gary Branch of the NAACP. Personally driven and fearless in pursuit of growth, she has completed a triathlon after learning to swim and celebrated her 50th birthday by running a half-marathon in Puerto Rico—a reflection of the same determination and passion she brings to every client partnership.