Upon returning to the U.S., he began a career in special education, but soon decided to quit and become part of the newly formed 1970s New York porn scene following an amateur appearance in Playgirl magazine—his then-girlfriend submitted a nude photo of Ron to the magazine. It was at this point that he decided to use his middle name Jeremy as his stage surname.

His venture into pornographic movies occurred during the "golden age" of pornography (1975 to 1983), an era marked by comparatively high production values and quality scripts (in this time, pornographic actors were expected to be at least minimally competent in dramatic acting). Though illegal to produce, adult films nonetheless were made and distributed to theaters rather than straight to video release. Jeremy's fame eventually grew, and he worked as 'special consultant' for the 1985 film Nine and a Half Weeks. Soon after leaving New York for California then Israel, he was arrested on two occasions and faced a lengthy jail sentence. He was reprieved due to the Hal Freeman precedent in the United States Supreme Court of 1988.

Despite being short, out of shape, overweight, and relatively unattractive, he has appeared in nearly 2,000 shorts, loops, and feature films to date and has directed a further 100. An uncommonly gifted performer, Jeremy is known for his superior cunnilingus skills, precise ejaculatory control, graceful money shots, and dogged physical stamina. He claims to get more work when he is on the heavy side, and for this reason he does not lose weight. He also claims to have had sex with over 4,000 women. According to Jeremy, every woman is beautiful---regardless of age, race, color, creed or size.

He is listed at the #1 spot on the "List of Top 50 Porn Stars of All Time" by Adult Video News magazine. He and the late John Holmes have appeared together in several films, often sharing female performers like Seka, Christy Canyon, Amber Lynn, and Ginger Lynn. He claims that, unlike some industry colleagues, he has never abused cocaine, alcohol, or other illicit substances. He also claims to never have contracted a sexually transmitted disease during his pornographic career, despite engaging in unprotected sex with thousands.

In 1996, Jeremy recorded a rap song with DJ Polo, produced by Dmitri Leybman, titled "Freak of the Week". The single was popular in the Miami bass music clubs and reached #22 on Billboard magazine's Hot Rap Tracks chart. Surprisingly, the music video featured a cameo appearance by Lynn Redgrave. He has also appeared in music videos such as Sublime's "Date Rape" and Kid Rock for the song "Cowboy", and in Moby's video for "We Are All Made of Stars," where he is shown making photocopies.

He has had small roles in a number of mainstream films: Detroit Rock City, 54, Ronin, Orgazmo, The Boondock Saints, Mr. Stitch, Art House, American Virgin, and Killing Zoe, along with various Troma films such as Terror Firmer. For some of these films, Jeremy paid his own airfare and other expenses just to get 45 seconds time[citation needed] in a non-pornographic film to show he can act without being naked. Ron was also a non-speaking extra in the first Ghostbusters movie. (1:08:12 into the film) In 2001, Jeremy was the subject of a documentary film, entitled Porn Star: The Legend of Ron Jeremy. In 2005 and 2006 he made the "Adult Associate", a spoof of Donald Trump's "The Apprentice" where he recruits for an assistant.

Jeremy has also appeared in a number of television series, such as the second season of the reality show The Surreal Life, a special "news makers" recording of the game show The Weakest Link, a cameo animated appearance as the host of the "Woody Awards" in episode 3.2 of Family Guy, Chappelle's Show, Mind of Mencia, Just Shoot Me, Bullshit!, Las Vegas and an uncredited appearance in NewsRadio

As further indication of his cross-over celebrity status, Jeremy has posed in an advertisement for PETA (People for the Ethical Treatment of Animals) to raise awareness of the over-population of domesticated animals. In the poster Ron lies partially nude on a bed, a pair of handcuffs around his wrist. Poking fun at his prolific notoriety, the title of the advertisement exclaims, "Too much sex can be a bad thing. Spay and neuter your cats and dogs."

Jeremy has also participated in debates on pornography at colleges around the US. One of these noted debates was against Susan Cole of NOW about the effects of porn on society at Middle Tennessee State University's (MTSU) campus. Jeremy was met with a couple of hundred protesters outside of the venue where the debate took place. Apparently there were rumors and confusion about his activities during the debate as some of the protesters thought he was going to be filming a porn on campus. The University also placed very tight restrictions on Jeremy's activities while at MTSU. He was not allowed any media interviews on campus, nor was he allowed to sign autographs or any other non-debate related activity at MTSU. The campus police escorted him onto campus two minutes prior to the debate, and escorted him off campus immediately following the debate thus limiting any interaction with students while on campus. In a local news interview prior to the event Jeremy remarked "this is by far the most restrictive University that I have spoken at yet".

In 2005, Jeremy again made headlines when he was invited to address the Oxford Union. According to the Union’s librarian, Vladimir Bermant, "Ron is the biggest and apparently the best in the business, so I'm sure he'll have some fascinating stories to tell." His speech defending pornography was well-received.

In 2006, Jeremy has begun a series of debates on pornography opposing Pastor Craig Gross, founder of the anti-pornography website xxxchurch.com, visiting various campuses as part of the "Porn Debate Tour." As Gross does not promote the banning of pornography, the debate centers on Gross' assertion that pornography is addictive, degrading, and unhealthy for both the actors and consumers, versus Jeremy's stance that pornography is normally a legitimate career and part of a healthy sexuality.