The song was written and produced by Steve Mac. It serves as the second single from The Wanted's second album, Battleground which was released on 7 November 2011. Band member Tom Parker said of the song, "We all felt it was a new, refreshing sound and a perfect song for the summer which really gets you in the mood for a party."
Robert Copsey of Digital Spy gave the song four out of five stars writing, "'I decided you look well on me/ So let's go somewhere no-one else can see/You and me,' they continue over a cantering beat and featherlight hook before launching into a carnival-inspired chorus fizzier than a frozen Daiquiri. 'My universe will never be the same/ I'm glad you came,' they croon on the outro. The result is their catchiest effort since 'All Time Low', though on repeated listens we're not buying this innocent act they're sporting one bit." David Griffiths wrote for 4Music that the song is "definitely their most danceable effort to date."About.com's Bill Lamb gave to the song 3.5 out of 5 stars, writing that the song has "genial vocals", a "pop-dance beat" and a "catchy synth hook", but he also noted that it has "frothy lyrics" and "little memorable weight to the song". He praised Max's solo in the beginning and also praised "the keyboard hook that nearly steals the show from the group." To conclude, he wrote that "Glad You Came" is a cheerful, uptempo tune that is easy to dance with, and it is little more than that.
Rolling Stone named "Glad You Came" the forty-fourth best song of 2012, citing the group's "push at the genre's PG-13 rating with a club-bumper that dares to raise the specter of under age inebriation."
"Glad You Came" debuted at number one in Ireland, making it the band's first number-one single in the country. The song was at number one for five weeks. In the United Kingdom, the song debuted at number one with first-week sales of over 117,000 copies, becoming the band's second number-one single in the UK. As of April 2014, it is their biggest-selling single to date with 590,000 copies sold in the UK.
In Australia the song was certified Gold for shipping 35,000 copies. In the United States, the song became their first to chart on the Billboard Hot 100, peaking at number three for four non-consecutive weeks after it was covered on the television series Glee, and becoming the highest American chart entry by a British boy band, surpassing Take That who peaked at number seven with "Back for Good" in November 1995. This record was broken by fellow British-Irish boy band One Direction when their single "Best Song Ever" peaked at number two on the Billboard Hot 100 in July 2013. As of May 2013, the song has sold 3,600,000 copies in the United States. The song was the best-selling song by a boy band in digital history before One Direction's "What Makes You Beautiful" overtook its sales in July 2012.
The music video was created by Director X and was filmed in Ibiza, Spain. It sees the band on the beach, in a club and at a houseparty each with an individual woman. It was uploaded to YouTube on 10 June 2011.Jay McGuiness revealed to MTV UK: "The theory of the video was take The Wanted to Ibiza and just film everything and then just cut bits that were useable. But the girls were models, they weren't just girls we picked." However Max George admitted: "Actually no, the girl I had to spend time with was just literally picked up off the street after a night out." The video has achieved over 115 million views on YouTube, becoming their most watched video on the site. It also starred a cameo from footballer John-Joe O'Toole.