On 5 July 2010, Iglesias released his ninth studio album Euphoria, his first work to be released under his new label Universal Republic. The album is Iglesias's first bilingual album, with seven original English songs and six original Spanish songs. It won the Billboard Music Award for Top Latin Album, the Billboard Latin Awards for Latin Album of the Year and Latin Pop Album of the Year, and was nominated for the Latin Grammy Award for Album of the Year. Iglesias worked with three producers whom he had collaborated with before: RedOne, Mark Taylor, and Carlos Paucar. The album features collaborations with Akon, Usher, Nicole Scherzinger, Sunidhi Chauhan, Ludacris, DJ Frank E, Pitbull, Juan Luis Guerra, and his third song together with Wisin & Yandel. In a joint venture with Universal Latino, Iglesias released different singles in both English and Spanish simultaneously to different formats.
The first English single from the album, "I Like It", which features the rapper Pitbull, was released on 3 May 2010 in the U.S. and became a success, reaching No. 4 on the Billboard Hot 100. The song was also featured in the MTV reality series Jersey Shore. "Cuando Me Enamoro" was released as the lead Spanish single from the album, and became the theme song of the Mexican telenovela of the same title, produced by Televisa. The song debuted at number eight and number twenty-five on the U.S. Latin Pop Songs chart and the U.S. Hot Latin Songs chart, respectively. It became his twenty-fifth top ten single on the U.S. Billboard Hot Latin Songs chart and after four weeks of its release date, it became his twenty-first No.1 song on this chart. In January 2011, the album's third English single, "Tonight (I'm Lovin' You)" broke into the top ten on the Billboard Hot 100, also reaching No. 4. The song was released only for digital download in the United States but was featured on some editions of Euphoria in Europe and some Asian areas. The song became Iglesias' first number one on the U.S. Pop Songs and Radio Songs airplay charts. A remix version of the album track "Dirty Dancer" was released as the fourth English single and became his ninth Hot Dance Club Play chart topper, tying with Prince and Michael Jackson as the male with the most No. 1 dance singles. Further, "Ayer" served as the album's third Spanish single and seventh single overall. The Euphoria Tour took Iglesias across the U.S., Canada, the U.K., and several European countries. One of the tour's legs took him to Australia, while fellow artist Pitbull joined him as an opening act. Prince Royce also served as opening act during the tour's second leg across North America.
Iglesias has collaborated with songwriter Guy Chambers to write "Un Nuovo Giorno", the lead single from Andrea Bocelli's first pop album. The song was later translated into English as "First Day of My Life" and recorded by Spice Girl Melanie C. The song has since gone to become a huge hit throughout Europe, and peaked in the number one spot in numerous countries. Iglesias also co-wrote the single "The Way" for American Idol runner-up Clay Aiken. Four songs co-written by Iglesias appear on the UK band The Hollies' 2006 album Staying Power. In 2010, Idol Allstars (Swedish Idol Series) released the song "All I Need Is You", co-written by Iglesias with Andreas Carlsson, Kalle Engström, and Kristian Lundin. He also co-wrote Jennifer Lopez's song "Dance Again", released in 2012, which reached number-one position in the Billboard Hot Dance Club Songs.
In 2010, Iglesias was included in the project Download to Donate, run by Music for Relief, an organization started by American rock band Linkin Park. He co-produced Download to Donate for Haiti, a charity album for the 2010 Haiti earthquake, with the co-vocalist of the band Mike Shinoda. Both of them promoted the album at various venues, one of them being Larry King Live, where he and Shinoda explained the project.