Katelyn Donnelly


Katelyn N. Donnelly is a highly skilled personal injury lawyer at the Cosse Law Firm who has dedicated herself to fighting for the rights of her clients. With a focus on cases involving vehicular collisions, traumatic brain injuries, and other complex personal injury cases, Katelyn has secured multiple six and seven figure outcomes for her clients, providing them with the justice they deserve.

  • Experience
    Practicing Since 2018
  • Education
    Louisiana State University, Paul M. Hebert Law Center at Louisiana State University


Katelyn N. Donnelly, a native from St. Bernard Parish, who now resides in St. Tammany, has been an Attorney with The Cosse Law Firm since 2018. Since joining the firm, Katelyn has secured multiple six and seven figure outcomes for clients. She advocates for clients in both State and Federal Court. She handles almost all types of personal injury cases, with a specialized focus on vehicular collisions, premises liability cases (i.e. trip or slip and falls), traumatic brain injury (TBI) cases, cases involving rideshare/app based companies, cases against political subsidiaries or governmental entities, road or highway defect cases, and commercial auto/commercial liability claims. Katelyn has the confidence and experience to aggressively advocate for her clients from the inception of a claim throughout the duration of the litigation process.

Professionally, Katelyn is a member of the Louisiana Bar Association, American Association for Justice, Louisiana Association for Justice, and the Academy of New Orleans Trial Lawyers. She is an active participant in multiple Traumatic Brain Injury Litigation Groups and attends conferences nationwide to retain the most cutting edge information available to aid in her effective representation of injured clients.

Educationally, Katelyn attended Archbishop Philip M. Hannan High School. She graduated magna cum laude, and went on to attend Louisiana State University in Baton Rouge. While at LSU, Katelyn studied Political Science, receiving a B.A. degree with a minor concentration in Communication Studies. She received her undergraduate degree in 2015. After undergrad, Katelyn continued her studies at the Paul M. Hebert Law Center at Louisiana State University. While in law school, Katelyn’s focus on mastering legal research and writing won her the CALI Excellence for the Future Award, the award given to the highest scoring student in any given course. She graduated in 2018 from the Paul M. Hebert Law Center with a Juris Doctorate and a graduate degree in Comparative Law.

In 1980, Katelyn’s father joined the Louisiana National Guard and began a daily routine of rising early, donning his boots, and selflessly protecting those around him. As Katelyn grew up, his unwavering dedication left a lasting impression. She knew early on she wanted to work in an environment that allowed her to help others. In her career as a personal injury attorney, she has the ability to do just that. Katelyn strives to emulate that selfless protection and advocacy for her clients day in and day out, fighting to achieve the results people deserve when they are injured through no fault of their own.

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