The next year, he was promoted to the major-league club and ended up becoming the closer after an injury to Kerry Ligtenberg. He finished the season with an earned run average of 2.13 in 38 innings pitched. proved to be Rocker's best year. After becoming the Braves' full-time closer, he converted 38 saves and had an ERA of 2.49 in 74 games. It was at this point that he was starting to be seen by many sportswriters as one of the next great closers in baseball.
During this same interview (which was conducted while driving to a speaking engagement in Atlanta), he spat on a Georgia 400 toll machine and mocked Asian women. Additionally, he referred to then-teammate Randall Simon, who is black, as being a "fat monkey."
Although Rocker later apologized after speaking with Hank Aaron and Andrew Young, he continued to make questionable remarks. For his comments, he was suspended without pay for the remainder of spring training and the first 28 games of the 2000 season, which on appeal was reduced to 14 games (without a spring-training suspension).
In June 2006, Rocker inserted himself into the Ozzie Guillén–Jay Mariotti controversy by defending his former teammate's right of free speech. "This is a free country. If he wants to use a lewd term, he should be able to use a lewd term," Rocker told the Chicago Tribune. "Can't you use a lewd term in America if you want?" . Referring to sensitivity training, he was quoted as saying "It was a farce, a way for the scared little man, Bud Selig, to get people off his ass." He claimed that when he attended mandatory sensitivity training he would seldom remain longer than 15 minutes. He also claimed he never paid the $500 fine that was levied against him.
In the eighth inning, Rocker came in to replace Jason Marquis. He was loudly booed and some objects were thrown and a chant of "Asshole, Asshole" began. Rocker struck out Robin Ventura, retired Todd Zeile on a grounder to short, and got Jay Payton to ground out to third. The Braves went on to win, 6-4. Rocker left the stadium a half-hour after the rest of the team in a black van trailed by three security vehicles.
Rocker made his screen-acting debut in the 2002 horror comedy The Greenskeeper as a murderous golf-club groundskeeper. He took the season off to recover from surgery on his left shoulder. In , he signed with the Long Island Ducks of the independent Atlantic League after training with the Chattahoochee Cougars in Alpharetta, Georgia. The Cougars later went on to win the AAAAA State Championship. In April 2005, he asked New Yorkers to "bury the hatchet." After going 0-2 with a 6.50 ERA in 23 games, he was released on June 27, 2005.
In 2006, Rocker appeared on the Spike TV network's Pros vs. Joes, a program that pits retired professional athletes against amateurs. He has also donated some of his earnings from baseball to various charities. He has said, "I've made some terrible choices in life — it's time that I started to give back to the community." Rocker has also spent some time in rehab for what he has called, "personal issues that if resolved, will make me a better person."
In late 2006, Rocker was interviewed by the popular sports blog, Deadspin along with girlfriend Alicia Marie. In the interview, Rocker discussed his "Speak English" campaign, as well as his upcoming book, which has yet to be published. Rocker stated that the book will not be used to try to repair his reputation, but will rather be "more conservative Republican rantings." Also during the interview, Rocker lambasted John Schuerholz, his former general manager with the Braves, calling him, "a real asshole," "an imbecile," "a complete moron," and "a piece of shit," while claiming that "he has the worst case of Little Man Syndrome I've ever seen." Rocker went on to say that his antipathy for the GM came after he felt Schuerholz misrepresented him in an arbitration case that Schuerholz eventually won.
Rocker's publicist, Debi Curzio said that Rocker admitted taking Human Growth Hormone, but only for medical reasons.
In April 2007, Rocker's father, Jake, died in a car accident in Warner Robins, Georgia.
In February 2008 Rocker said in an interview on Atlanta radio stations Rock 100.5 and 680 The Fan, "Bud Selig knew in the year 2000 John Rocker was taking the juice.