García was hired by the World Wrestling Federation as a ring announcer in 1999. She made her debut on the August 23, 1999 episode of Raw is War in Ames, IA. She was involved in her first angle on the September 13 episode of Raw is War, when Jeff Jarrett applied a figure four leglock to her after she angered him by announcing his loss by disqualification to Luna Vachon.
Garcia's second angle occurred on the December 13, 1999 episode of RAW. Lilian introduced Miss Kitty for a Women's Championship chocolate pudding pool match. After Lilian announced her, Miss Kitty grabbed the mic and informed Lilian that she was now to be known as "The Kat". Her opponent, Tori, came out for their match and right after the two women began, X-Pac came poolside in a skin diving suit complete with snorkel, flippers, and goggles. As he was adjusting his goggles Tori jumped on his back causing both of them to fall into the pool with X-Pac landing up on top of Tori, giving Miss Kitty an easy pinfall. Lilian announced the winner as "Miss Kitty", which infuriated The Kat, who threw Lilian into the pool of pudding.
García sang in the WWF for the first time on February 14, 2000 at a house show, and began singing "The Star-Spangled Banner" at television tapings later that month. Her first televised performance was on April 2, 2000 where she opened WrestleMania 2000. Following the September 11 attacks, Garcia sang "The Star-Spangled Banner" on the September 13, 2001 episode of Smackdown!, receiving a standing ovation. In the course of the evening, Garcia commented on the attacks, saying "Well, to say the least, this has been a real roller coaster of a week. And especially because I live in New York City. Um, I have loved ones there, and I'm just very fortunate and very glad that a specific one didn't get to go to his meeting at 8:30 in the morning that he was supposed to be at the Twin Towers, and uh...so I thank God for that, and I still don't know about a lot of my friends. I have...uh, we'll be finding out, I guess, little by little. I pray for everybody there...".
In mid-2002, García briefly "feuded" with rival announcer Howard Finkel after Finkel left her to be decimated by 3-Minute Warning, culminating in an "evening gown versus tuxedo match" that Garcia won with the assistance of Stacy Keibler and Trish Stratus.
In June 2005, García began an on-screen romance with wrestler Viscera. The angle saw García propose to Viscera, stating that she wanted to marry him during the Vengeance pay-per-view on June 26. The angle ended at Vengeance when Viscera rejected Garcia in favor of The Godfather's "Hos". The angle was briefly resurrected eleven months later when Viscera proposed to Garcia on the May 22, 2006 episode of Raw, but was interrupted by Umaga before receiving an answer.
García took part in her first major Diva publication in 2005 with the release of the Divas 2005 swimsuit magazine and related DVD Viva Las Divas of the WWE.
On the June 5, 2006 episode of Raw, Garcia (legitimately) suffered a sprained wrist when wrestler Charlie Haas inadvertently knocked her to the ground as she stood on the ring apron. One week later, the accident was metamorphosed into a storyline, with Haas incurring the wrath of Viscera. The storyline ended on the July 10, 2006 episode of Raw, when Viscera "accidentally" performed a Samoan drop on Garcia while confronting Haas. Garcia was removed from television for several weeks in order to sell the Samoan drop.
García took part in her second major Diva publication in 2007 with the release of WWE Divas Do San Antonio, in honor because WWE was in San Antonio for the Royal Rumble.
On the April 2, 2007 episode of Raw, García was humiliated in the ring when her blue satin frilled skirt was torn off by Bobby Lashley, revealing black nylon panties after Vince McMahon attempted to hide his newly shaven bald head under her skirt. The incident resulted in a large surge in searches for Garcia on the Internet, with searches for "Lilian Garcia" jumping 301% and becoming the fourth most searched-for term on the search engine Yahoo!. She returned to announcing on the July 2, 2007 edition of Raw after taking time off to recover from a skiing injury in which she tore the ACL in her right knee. She was not fully recovered as was evident from her only announcing the first two matches from the ring and the rest from the floor.
On the August 6, 2007 edition of Raw, Garcia announced her new album entitled "Quiero Vivir". Lilian then started a feud with Jillian Hall, who claimed to be a better singer than Lilian. The next week, she competed in WWE Idol, a parody of American Idol, in which she sang "New York, New York" by Frank Sinatra before being interrupted by Santino Marella.
During the last week of August 2009, Garcia celebrated ten years with WWE, becoming WWE's first and only "Decade diva". Lilian debuted in August of 1999.
On the September 21, 2009 edition of Raw from Little Rock, AR, Jerry Lawler announced to the live audience that it was Garcia's final night with WWE. Garcia then made an emotional speech in the ring, thanking the fans and all of her colleagues. The final match she announced saw Randy Orton, Chris Jericho and Big Show taking on the team of John Cena, Montel Vontavious Porter and Mark Henry, although a match between Primo Colon and Chris Masters was taped earlier that evening and aired three days later on WWE Superstars, Garcia's final appearance on WWE television. She is now focusing on her singing career