[5] He is the son of Grover C. Cobb, a radio station owner who was senior executive vice-president of the National Association of Broadcasters (which named one of their prestigious awards for him).

[6][5] Cobb's father was vice-president and general manager of KVGB (AM)/FM in Great Bend,[7] and had a key role in forming the Kansas Association of Broadcasters.

Cobb reportedly is a distant relative of the Hall of Fame baseball player bearing the same name,[8] but the specific genealogy is not known.

[10] Cobb served as a law clerk for a federal judge,[6] then became Assistant U.S. Attorney for the District of Maryland in 1981-86 based in Baltimore[2] as chief of the criminal section and head of the region's drug enforcement and organized crime task force.

[13] Cobb successfully defended Hudson Foods against allegations that its executives lied to investigators after a recall of beef tainted with E. coli.

[11] Other high-profile clients have included Eli Segal, Mary McCarthy, AIG, Office Depot, the House of Saud, IBM, and Medtronic.

[11] Cobb joined the White House to manage matters related to FBI Director Robert Mueller's special counsel investigation into Russian interference in the 2016 United States elections, starting on July 31, 2017.

"[23] Since leaving the White House, however, Cobb has criticized Trump, calling him "a disaster for the Republican Party"[24] and accusing him of "stifling truth.