In 1985, Astley was playing the club circuit as a drummer with a soul band named FBI when he was noticed by the record producer Pete Waterman and persuaded to come to London to work at the PWL recording studio.

Under the tutelage of the production team of Mike Stock, Matt Aitken and Pete Waterman, known as Stock Aitken Waterman, Astley was taught about the recording process and groomed for his future career, supposedly starting off as the recording studio 'tea boy'.

During much of his career, due to his deep bass-baritone voice, many listeners assumed he was black. In one instance, the comedic entertainer Sinbad discussed him with a talk-show host, expressing his surprise that Astley was not "one of the brothers."

In another, it was widely believed for years that he was the voice behind the chorus of Cathy Dennis' song "Just Another Dream", when in fact the true singer was a black disc jockey known as Dancin' Danny D. Even after his visual appearance, it was still popular belief that he was miming for a black American singer. His brother Mike Astley helped to refute this assertion.

His first single was the little-known "When You Gonna," released as a collaboration with Lisa Carter, but his first solo offering was "Never Gonna Give You Up," released in 1987. It became an immediate success, spending five weeks at the top of the British charts and becoming the year's highest-selling single. It was the first of 13 (world-wide) top 30 hit singles for him.

The album Whenever You Need Somebody also reached number one in the UK, and the hit singles continued, including the title track and a cover of Nat King Cole's "When I Fall in Love."

On 12 March 1988, "Never Gonna Give You Up" also topped the U.S. singles chart and was followed by a second U.S. #1 on 18 June with his second U.S. single release, "Together Forever." In 1989 he was nominated for a Grammy Award for Best New Artist of the Year. He lost to Tracy Chapman.

By the end of the decade, Astley had parted company with Stock Aitken Waterman. He achieved one more major success with the 1991 ballad "Cry for Help," which reached the top 10 in both the UK and the US.

In 1991 the RIAA certified that two million copies of Whenever You Need Somebody had been sold. Total world sales of Astley's records (including singles, albums and compilation inclusions) have since reached 39.9 million.

His next album, Body and Soul, was released in 1993. The album did not chart in the UK but managed to make the Billboard 200, peaking at #182.

The two singles, "The Ones You Love" and "Hopelessly", performed very well on the adult contemporary chart, peaking at #19 and #4 respectively. "Hopelessly" also crossed over and peaked at #31 on the Top 40 Mainstream chart.

For much of the 1990s and early 2000s, Astley remained largely out of the spotlight.