Lead singer Chris Martin said that the lyrics are about being devoted to someone, wanting to do anything for them: writing a song for them, swimming across the sea for them and so on. It's not necessarily a romantic devotion, but could be about someone that you look up to and would do anything for, a brotherly love. He claims to have had no specific person in mind when he wrote it.

The band came up with the line, "Look at the stars, look how they shine for you" after looking up at the night sky. They were recording at Rockfield Studios in rural Wales, where Queen famously recorded "Bohemian Rhapsody" in 1975. It was a nice, clear sky, and Coldplay's producer, Ken Nelson, said, "Look at the stars, lads." Martin proceeded to write "Yellow" in 10 minutes. Another famous song influenced by the Rockfield landscape is "Wonderwall" by Oasis, which Noel Gallagher sang on a stone wall on the grounds. Because, you know, it's Wonderwall.

The color yellow can have many negative implications (yellow journalism, yellow fever, a yellow card for a foul in soccer), but for Coldplay, it is a beautiful color. According to lead singer Chris Martin, "It was simply because that word sounded nice, it just seemed to fit, no other reason. None of the other colors would have sounded right really!" The Beatles were also kind to the color when they used it in their song "Yellow Submarine."