Wesson served in the California State Assembly, representing the 47th district from 1998 until 2004. He was unanimously elected Speaker of the California State Assembly in January 2002 and served in the role until February 2004. He was the second African-American to be elected Speaker of the California Assembly. His legislative agenda focused on education, environmental protection and healthcare.
In July 2015 he created a committee that would address how Los Angeles could be more business-friendly. Some of the developments in the 10th Council District during Wesson's term have been Midtown Crossing, Kaiser Permanente Baldwin Hills/Crenshaw Medical Offices, and Cumulus.
Race relations
On October 20, 2016 Wesson announced the creation of embRACE L.A., a program to engage Angelenos in a conversation on race, ethnicity and diversity. He partnered with Councilmember Mitch O'Farrell to create the program. On April 25, 2017 Wesson invited over 20 members of the community to dinner at his home to discuss embRACE L.A. and race in Los Angeles.
Olympic bid
Wesson chaired the City Council's Ad Hoc Committee on the 2024 Summer Olympics. On January 25, 2017 he voted in favor of final approval of L.A.'s Host City Bid. Following the news that L.A. would bid on the 2028 Olympic and Paralympic Games, Wesson and the City Council voted unanimously in favor of the new proposal. On September 13, 2017, Los Angeles was officially named as the host of the 2028 Olympic and Paralympic Games.
Immigration
On December 19, 2016, the City Council created a $10 million fund to provide legal assistance for Los Angeles residents facing deportation On January 20, 2017, Wesson was part of the City Council action that approved the hiring of an "immigrant advocate". On April 20, 2017 Peter Schey was appointed to the position. In April 2017, Wesson welcomed a delegation of governors from Mexico to discuss the relationship between Los Angeles and Mexican states. He concluded the dialogue by making each member of the delegation an honorary citizen in the City of Los Angeles.
Controversy
On October 24, 2019 the Los Angeles Times wrote a story accusing Wesson's son of receiving discounts on his rent at an L.A. apartment building. Rent records showed that over the years, the building had increased rent for the nearly all of its tenants except Wesson's son. Separately, Herb Wesson had helped the building's owners win approval of a controversial high-rise.
Each summer Wesson hosts several screenings in the 10th Council District of various family-friendly flicks. Dubbed "Movies in the Park", the series provides a fun and safe environment for all ages. In addition to the movie screenings, Wesson provides all attendees with a meal, drink, popcorn, candy and a raffle drawing. Each year, the series sees thousands of attendees across the four film screenings.
Winter Wonderland
Wesson's Winter Wonderland includes a tobogganing course made from real snow, holiday themed arts and crafts, lunch and an appearance from Santa Claus. Wesson also gives toys to all attendees and raffles off larger prizes such as bicycles. In December 2015 Wesson gave computers to 350 families.