Mathews was eventually hired by World Wrestling Entertainment, and began using the name "Josh Matthews". In December 2002, he began appearing as the backstage interviewer for the SmackDown! brand and as an announcer on WWE Velocity. In January 2003, his name was tweaked to Josh Mathews. He also hosted the WWE webcast Byte This! after Kevin Kelly was released. He later hosted several shows on WWE's official website including Weekly Top 5, The WWE Experience, and WWE After Burn, the latter two of which are televised internationally.
In 2004 Mathews was given some limited ring-time on SmackDown! when John "Bradshaw" Layfield slapped Mathews for not showing some respect to his chief of staff Orlando Jordan when he was interviewing him. He later offered and was accepted to be Booker T's temporary partner for a tag team match on an episode of SmackDown!. He and Booker ultimately won that match. He was later assaulted by Jordan and requested from General Manager Theodore Long that he be given a one-on-one match against him. Booker T wanted to be at ringside during the Mathews-Jordan match, as JBL would no doubt be present, and would give Booker T an excuse to beat down JBL before their match at Survivor Series. Mathews would once again emerge victorious against Jordan, with some considerable help from Booker T. He also tried to help Booker in his WWE Championship match at the Survivor Series, but was given a Clothesline From Hell by JBL for his efforts. On March 31, 2005 episode of Friday Night SmackDown! Mathews was attacked by Kurt Angle. Mathews was then (kayfabe) possessed by The Undertaker on the December 9, 2005 episode of Friday Night SmackDown! while interviewing Randy Orton.
Mathews filled in for an absent Todd Grisham on a summer 2006 episode of Raw. He also hosts pre-shows for WWE pay-per-view events, and he provided color commentary on Heat from time to time before the show was cancelled in May 2008. He was the host of WWE.com's Weekly Top Five when it started and hosted it until April 2009 when he was replaced by Jack Korpela. During Todd Grisham's stint as ECW commentator, Mathews replaced him as Raw's backstage interviewer.
On the April 7, 2009, episode of ECW, Mathews was announced as the new play-by-play commentator, as the previous commentator, Todd Grisham was moved to SmackDown after Tazz departed WWE. In addition to commentating on ECW and ECW pay-per-view matches, Mathews along with Matt Striker would represent the ECW brand on WWE Superstars every week starting with the inaugural episode on April 16, 2009. After ECW's closure, Mathews became the Color commentator of WWE NXT. On the April 9, 2010 episode of SmackDown, Mathews was attacked with a sleeper hold by Dolph Ziggler when he was interviewing him. On December 10, Josh Mathews officially replaced Todd Grisham as the play-by-play commentator for SmackDown, commentating alongside Michael Cole. On the February 4, 2011, episode of SmackDown, Mathews and Cole were joined by Booker T, forming a three-man announce team. Mathews was replaced by William Regal as a commentator on season five of NXT in 2011.
In late 2010, Mathews also very often worked as the color commentator on Raw due to Jerry Lawler's increased in-ring competition. On April 3, 2011, Mathews commentated the majority of WrestleMania XXVII, though he received a 'Stone Cold Stunner' from an angered Stone Cold Steve Austin, cutting his night short.
The following night on Raw, Mathews found himself aligned with Jerry "The King" Lawler, and against Michael Cole. He would then become the alternate spokesman for the anonymous Raw General Manager, when Michael Cole was not commentating. On the April 25th edition of Raw, Mathews announced that the Jim Ross and Jerry "The King" Lawler vs. Michael Cole and Jack Swagger match at Extreme Rules will be a Country Whipping Match, in which Cole and Swagger would win. On the following pay-per-view, at Over the Limit, Mathews supported Lawler, Bret "The Hitman" Hart, and Eve Torres in having Michael Cole kiss Lawler's foot. The following night, again as the spokesman for the anonymous Raw General Manager, Mathews read the e-mail that the General Manager denied The Miz's request for another title shot, seemingly done with John Cena.
He would leave the Raw broadcasting table the following week, after Cole and Lawler (somewhat) reconciled and became a duo again, though he remains on the show as a backstage interviewer/backup commentator. He was reunited with his former ECW and Smackdown broadcast partner Matt Striker on the November 10, 2011 episode of Superstars, becoming the new fulltime broadcasting team.
Mathews and Striker also called the November 9, 2011 broadcast of NXT, thus marking his second return to the show since his run as NXT commentator ended after Season 4. On the April 23, 2012 episode of Raw, Matthews was throttled by Brock Lesnar after Lesnar believed Mathews had made a smart-aleck comment towards him. Later in the year, he was attacked at Summerslam, this time by Kane, who was angry over being defeated by Daniel Bryan. Matthews was once again attacked by Kane on the August 31, 2012 episode of Smackdown after he lost his match against Alberto Del Rio.
Mathews became the play by play commentator of Saturday Morning Slam upon the show's debut on August 18, 2012 on The CW. Two months later he joined former adversary JBL to become the new Smackdown commentary team. On September 27, 2013, he started as commentator of Superstars with Tom Phillips. On October 18, 2013 edition of SmackDown, Alberto Del Rio attacked Matthews while threatening John Cena about what he was going to do to him in Hell in a Cell. Starting in February of 2014, Mathews began being the host of the Raw and SmackDown pre and post shows as well as PPV pre and post shows along with Booker T and Alex Riley on the newly launched WWE Network. On June 25, 2014, Mathews was released from WWE.