His mother, Marnie (née Fahr), was a remedial reading teacher at the Brooklyn House of Detention, and his father, Roy Henry Steyer, was a partner in the New York law firm of Sullivan & Cromwell.

In an article in the Los Angeles Times, Steyer's college friend, Mike Tollin, said "[Jim's] whole focus on kids comes from his close relationship with his mother…She was the kind of woman who would sit you down, ask you how things were, and you felt like you needed to tell her the truth.

"[13] Steyer graduated early from Phillips Exeter Academy in New Hampshire and worked with his mother teaching remedial reading at a public school in Harlem.

There, he helped spearhead the Poverty and Justice Program, focused on developing national legal and legislative strategies on behalf of disadvantaged African Americans.

In response he started JP Kids in 1996, a for-profit company that produced such shows as The Famous Jett Jackson, which aired on the Disney Channel.

JP Kids also provided an online outlet for teens to share opinions, explore alternative points of views and discuss political and environmental topics.

[27] In 2011, the New York Times reported that Steyer was helping build the Center for the Next Generation, a nonprofit that aims to influence public policy debates focused on national children's and energy issues.

[32][19] Steyer currently leads a Stanford course lecture, featuring guest speakers such as Condoleezza Rice, Thomas Friedman, Jim Mattis, Nicholas Kristof, and Reid Hoffman.

[33] Steyer launched the Future of Tech Commission with former Massachusetts Governor Deval Patrick and former Education Secretary Margaret Spellings as co-chairs, in April 2021.

The commission will compile solutions for a comprehensive tech policy agenda, under President Biden and The United States Congress, on topics such as privacy, antitrust, digital equity, content moderation and platform accountability.

Common Sense Media distributes its content to more than 100 million US homes via partnerships with Comcast, Time Warner Cable, DIRECTV, NBC Universal, Netflix, Best Buy, Google, Yahoo!, AOL, Huffington Post, Fandango, Trend Micro, Verizon Foundation, Nickelodeon, and more.

Their education programs focus on digital literacy and citizenship for students & parents and are in use in more than 90,000 schools across the U.S.[38] Common Sense Media played a major role in the passage of the 2005 California law restricting the sale of violent video games,[15] but was struck down by the Supreme Court.

[41] In January 2024, the first annual Common Sense Summit on America’s Kids and Families was held, featuring speakers such as Vivek Murthy, Hillary Clinton, and Sam Altman.

According to Stanford Magazine, the book "paints a frightening picture of greedy media companies, indifferent government regulators and parents too overwhelmed to pay attention.

During a May 2012 segment of NPR's Fresh Air with Terry Gross, Steyer noted that, "In a world where everything's photographed, where kids are constantly snapping photos on their cellphones and where youthful indiscretion is exactly the same as it's always been, the consequences can be much greater".

Bruce Reed, Deputy Chief of Staff to President Joe Biden, co-wrote a chapter pushing for reforms of the Communications Decency Act.