In 2004, Radin's friend Cary Brothers gave a demo featuring Radin's first composition, "Winter", to American actor Zach Braff, who promptly used it to score a scene in the hit television series Scrubs. Others found Radin's music just as evocative and soon various Radin songs were heard on TV shows such as Grey's Anatomy, Brothers and Sisters, American Idol, One Tree Hill, and So You Think You Can Dance, as well as movies including The Nanny Diaries, The Last Kiss, and Catch and Release. In 2004 he appeared in the film Garden State as a cameo appearance co-starred Zach Braff.

Radin's debut album, 2006's We Were Here drew critical acclaim and passionate listener response. His favorite song is "You Got Growin' Up To Do". Radin has had a number of well known musicians on his studio recordings, including Ryan Adams who played guitar on the song "Lovely Tonight".

Radin has achieved success in the UK and Europe where he has been promoting his top 10 record "Simple Times" and his single "I'd Rather Be With You" which reached #2 on the charts. He recently concluded a sold-out tour and will return to the UK in mid 2010 to play at several festivals, from Glastonbury, to Hard Rock Calling, to Oxegen. After the success of his first single, Radin released the 2nd single off the UK release of Simple Times, "Brand New Day." There is a video to accompany the song that can be viewed on his websites.

In the US, Radin released a new EP, "Songs Under A Streetlight", with the new US single, "Streetlight". The EP, out exclusively on iTunes, debuted at #1 on the Alternative Chart, and #5 on the overall iTunes chart.

Released on Columbia Records in 2006, We Were Here presented the first batch of songs Radin ever wrote. The album drew critical acclaim and received a 4-star review from Rolling Stone, who praised it for Radin's "whispery, silver-bell voice" and its themes, calling them "poignant and refreshingly frank." The record hit No. 1 on the iTunes Folk Album Chart.

For his second full-length album, Simple Times, Radin enlisted highly regarded producer Rob Schnapf (Elliott Smith, Beck). The two spent seven weeks recording at L.A.'s legendary Sunset Sound Studio working with a cast of musicians that included guitarist Greg Leisz, bassist Johnny Flaugher, keyboardist Jason Borger, drummer Victor Indrizzo and percussionist Lenny Castro. Among the album's many highlights are "You Got Growin' Up To Do," featuring guest vocalist Patty Griffin, lead single "I'd Rather Be With You" and "Brand New Day." Tracks from the album were featured on TV shows such as "Bones," "Scrubs," "House," "Grey's Anatomy," "One Tree Hill," "90210," "Brothers and Sisters" and "American Idol," among others.

Upon turning in his sophomore album Simple Times to Columbia Records, the label told him he had to add a song to the collection that would be more of a radio hit. Not wanting to kowtow to the label bigwigs, Radin decided to give all their money back to them and go it on his own. Shortly thereafter he found a new independent label Mom & Pop Music to release Simple Times without changing it at all and upon release, the album went to number 1 on the overall iTunes chart. On Monday April 12, 2010 Simple Times was released in the UK. On the same date, at a show at the O2 Academy Birmingham, Radin announced he had completed the final track of his third album,The Rock and the Tide. The album is set to be released October 12, 2010.

Over the course of his career, Radin has shared stages with artists such as Sheryl Crow, Tori Amos, Imogen Heap, Meiko, Missy Higgins, Maria Taylor, Gary Jules, Amber Rubarth, Schuyler Fisk, and many more. His first sell-out crowd was in Minneapolis.

In January 2008, Joshua performed the song "Today" on The Ellen DeGeneres Show after meeting the talk show host at a charity event the weekend before. Ellen later asked Radin to perform the song at her wedding, reportedly having turned down song offers from George Michael and Justin Timberlake.