Calderon ran for the seat vacated by his brother Tom and won the Democratic primary with 46% of the vote.

Calderon was elected to the 30th Senate District, which includes: Bell, Bell Gardens, Commerce, Cudahy, Huntington Park, La Mirada, Los Angeles, Montebello, Norwalk, Pico Rivera, California, Santa Fe Springs, South El Monte, South Gate, Whittier, East Whittier, East Los Angeles, Florence-Graham, Hacienda Heights, South Whittier, and West Whittier-Los Nietos.

In the Democratic primary, Calderon defeated fellow State Representative Rudy Bermúdez 50.4%-49.7%, a difference of just 305 votes.

[4] In August 2011, Calderon announced he would be running for the United States Congress in the newly redrawn California's 38th congressional district against incumbent U.S. Congresswoman Linda Sánchez in the Democratic primary.

[15] On June 4, 2013, the Federal Bureau of Investigation (FBI) raided Calderon's offices in the California State Capitol in an attempt to find evidence regarding accusations of criminal activity.

[16] An FBI affidavit was published online on October 30, 2013, by cable network Al Jazeera America with a claim that State Sen. Ron Calderon accepted about $88,000 in bribes from a Southern California hospital executive, Michael Drobot, for legislation regarding workers' compensation for an expensive surgical procedure, and an undercover FBI agent posing as a film studio owner during a wide-ranging probe into his conduct as a legislator.

[19] After surrendering to authorities on February 24, 2014, Calderon appeared in Court and pleaded not guilty to 24 charges relating to wire fraud, bribery, money laundering and falsification of tax returns.

[21] On June 13, 2016, federal prosecutors announced that Calderon agreed to plead guilty to mail fraud.

[23] In October 2016, Calderon was sentenced by U.S. District Judge Christina A. Snyder to serve 42 months in federal prison and perform 150 hours of community service.

[2][24] Through his attorney, Mark Geragos, he had petitioned the Bureau of Prisons to be released 12 month earlier, in January 2018, under the Second Chance Act of 2007.