Following his law school graduation, Chu served as a law clerk for Hon. Charles M. Merrill, U.S. Court of Appeals for the Ninth Circuit. In 1977, Chu went to work as an associate at the Los Angeles law firm of Irell & Manella. Chu was elevated to partner in 1982, and became the firm's co-managing partner in 1997, serving two terms until 2003. Chu is known for his many high-profile trials involving technology including:

- In 2002, Chu won a $500 million jury verdict for City of Hope against Genentech. Punitive damages were later reversed by the California Supreme Court, but the compensatory damages represent the largest judgment ever affirmed on appeal in California. The defendant ultimately paid a judgment of over $480 million including interest.

- Chu won a $120 million jury verdict for Stac Electronics against Microsoft. The trial court entered a worldwide injunction against Microsoft's flagship product, the MS-DOS operating system, and then the case settled.

- Chu was co-counsel for the plaintiff in Texas Instruments v. Samsung, which resulted in a settlement for the plaintiff of more than $1 billion.

Morgan Chu has secured many of the world’s largest – and in some cases precedent-setting – verdicts, judgments and settlements, resulting in actual payments totaling more than $9 billion. His decades-long career stands apart for its impact and influence. He has been described by clients in Chambers USA as “beyond doubt the most gifted trial lawyer in the USA” who “delivers staggering results for clients.”

In March 2021, Chu co-led the trial team that secured a $2.2 billion jury verdict for VLSI Technology in a patent infringement suit against Intel involving microprocessor technology. The result was the second-largest patent verdict in U.S. history. His strategy included ensuring that technical issues surrounding Intel’s infringement were easily understandable for the jury, and focusing on real-world benefits Intel obtained from using VLSI’s patents. The jury found both patents infringed and rejected Intel’s invalidity case. Chu is co-leading Irell teams representing VLSI in several additional infringement cases.