He is a former United States Attorney for the Northern District of Illinois and previously served as the Special Counsel in the Iran-Contra affair.

[1] As U.S. Attorney, Webb led Operation Greylord and successfully prosecuted 76 corrupt judges, police officers, court clerks, and lawyers.

To date, OCDETF, which comprises 2,500 law enforcement agents from eleven federal agencies including the FBI, DEA, ATF, ICE, IRS, U.S.

Marshals Service, and U.S. Customs and Border Protection, has conducted operations that have led to 44,000 drug-related convictions and the seizure of over $3 billion in cash and property assets.

[9] Webb previously served as Special Counsel in the Iran-Contra affair and successfully prosecuted Admiral John Poindexter, President Ronald Reagan's National Security Advisor, for lying to the United States Congress and obstructing their investigations.

[11] In 2012, Webb was the special prosecutor in the case involving David Koschman, who died after being punched by the nephew of then-Chicago Mayor, Richard M. Daley.

He is the co-executive chairman of Winston & Strawn, an international law firm with nearly 1,000 attorneys in 16 offices in the United States, Europe, Asia, and the Middle East, with gross revenue of $985 million in 2017.

[14] Webb represented Bill Gates and Microsoft in the United States v. Microsoft Corp,[15] the New York Stock Exchange as chief counsel in a dispute involving $120 million in compensation paid to their former chairman and CEO Richard Grasso,[16] General Electric in a price-fixing case,[17] Philip Morris in its $300 billion tobacco-related litigation,[18] Verizon in obtaining a $58 million verdict in a patent litigation matter with Vonage,[19] Guggenheim Partners in litigation related to their $2.2 billion acquisition of the Los Angeles Dodgers,[20] Beef Products Inc. in obtaining over $177 million, the largest ever settlement in the United States for a media defamation case,[21] and other Fortune 100 corporations in litigation including BP, Boeing, JPMorgan Chase, Ernst & Young, Pfizer, and Deloitte.

[21] Webb has also represented Jack Welch, former chairman and CEO of General Electric, in his divorce and numerous personal matters,[29] the city of Ferguson, Missouri to negotiate and litigate reforms with the United States Department of Justice following the shooting of Michael Brown,[30] the children of Hyatt hotel heir Robert Pritzker in connection with allegations that their family trust funds were looted of about $1 billion,[31] and billionaire Rishi Shah's Outcome Health in an internal investigation, following an exposé in The Wall Street Journal that alleged employees misled advertising clients.

[34] Other corporations that Webb has represented include American Airlines, Alcoa, Charles Schwab, ConocoPhillips, Cisco Systems, Heinz, Bacardi, Cargill, State Farm, Motorola, and Express Scripts.

In 2023, Pat Fitzgerald retained Webb to represent him following his firing as head coach of Northwestern Wildcats football team as a result of the school's hazing scandal.

[40] Abbe Lowell, Webb's partner at law firm Winston & Strawn, represents the President's son-in-law Jared Kushner and daughter Ivanka Trump in the investigation,[41][42] and Webb represents billionaire Dmitry Firtash, a business partner of Paul Manafort, the former chairman of Donald Trump's presidential campaign.

[44] Alongside Lanny Davis, defense attorney for President Trump's former lawyer Michael Cohen, Webb also represents billionaire Ukrainian oligarch Dmitry Firtash should he be extradited to the United States to face charges of bribery.

[49] Jenner & Block chairman Anton R. Valukas, bankruptcy examiner in the Bankruptcy of Lehman Brothers, called Webb "a stunningly good trial lawyer", and Brendan Sullivan, defense counsel in the Duke lacrosse case, remarked that Webb is "one of the most formidable courtroom lawyers in America today".