After graduating from law school and being admitted to the Alabama State Bar in 1993, Brinyark began his legal career practicing in Tuscaloosa County. He is licensed to practice in all Alabama State Courts as well as the U.S. District Courts in the Northern and Middle Districts of Alabama. In 2009, Brinyark became a shareholder of the firm Rosen Harwood, P.A., where he headed the Domestic Relations practice area until launching Brinyark & Frederick, P.C. in 2014. His law firm specializes in divorce law, estate planning, business law, and real estate.

Brinyark's judicial service began in 2000 when he became a reserve Municipal Court Judge for the City of Tuscaloosa. He subsequently served as Municipal Court Judge for the City of Brent beginning in 2003, the City of Centreville starting in 2005, and the Town of Woodstock from 2015. He also contributed to the Alabama Judicial Study Commission, where he drafted the Continuing Education Rules for City Judges.

His involvement in the legal profession extended beyond his practice and judicial roles. Brinyark served as President, Vice President, and Secretary/Treasurer of the Tuscaloosa Bar Association from 2003 to 2005. He is a member of the Alabama and Tuscaloosa Bar Associations as well as the Alabama Municipal Judges Association. Additionally, he has served on the Tuscaloosa County Bar Association Grievance Committee, the Alabama Black Belt Action Commission, and the Alabama Judicial Study Commission.

Brinyark's political career began in 2023 when he announced his candidacy for the Alabama House of Representatives District 16 seat, which became vacant after Kyle South's resignation. In the Republican primary held on September 26, 2023, Brinyark finished second with 33.0% of the vote, advancing to a runoff against Brad Cox. He won the runoff election on October 24, 2023, with 52.8% of the vote. In the general election held on January 9, 2024, Brinyark defeated Democratic candidate John Underwood with 83.4% of the vote.

Since taking office on January 10, 2024, Brinyark has served on several House committees including the Judiciary Committee, Health Committee, Jefferson County Legislation Committee, and Tuscaloosa County Committee. During his first year in office, he sponsored multiple bills that were signed into law, including legislation related to game breeder licenses, Fayette County revenue commissioner duties, sheriff's compensation, agricultural assessments, and municipal zoning boards.

Brinyark was previously married to Mildred Elizabeth Murphree, with whom he had at least one child. The couple divorced, and court documents from their divorce proceedings became public in 2015. Brinyark is the father of five children- Tanner, Tyler, Clayton, James, and Helen. All of his children graduated from Northside High School and the University of Alabama. His son James was recognized on the University of Alabama Dean's List in Spring 2019.

Brinyark has been active in community service throughout his career. He previously served as Chairman and Baseball President of Northside Park in Tuscaloosa. He also chaired the Board of Tuscaloosa Shooting Sports Inc. and was a board member of Indian Rivers Behavioral Health, appointed by the County Commission. Brinyark is a member of Northport Church of Christ and maintains a lifetime membership in the National Rifle Association. He has resided in the Samantha/Windham Springs area for 19 years, where he raised his family on a small farm.