Ratcliffe joined Everton as an apprentice in 1977 and made his debut on 12 March 1980 at Old Trafford, Manchester after replacing John Gidman through injury, but was not a first team regular until 1982. He was initially used as a left back with mixed results, but his form improved dramatically when moved to centre back. Around this time Ipswich Town manager Bobby Robson was interested in Ratcliffe, but at the PFA Awards that year Howard Kendall reputedly told Robson to "F*** O**" showing his confidence in the young Ratcliffe. In 1983 at the age of 23 he was made captain, just as the club began a highly successful spell. Whilst captain Ratcliffe won the 1984 FA Cup Final, the Football League Championship in 1984–85 and 1986–87 and the UEFA Cup Winners' Cup 1984–85. There were also two other FA Cup finals. Ratcliffe made 461 appearances for Everton and scored two goals in that time (one a 30-yarder at Anfield).
Ratcliffe was renowned for his robust approach to the game and for being a tough tackler. He was sent off early in his career for a head butt in 1981 on Tommy Hutchison against Manchester City in 1981. He was also involved in an infamous incident with Vinny Jones in 1989 against Wimbledon. In a bad tempered match, Jones had put in a late tackle against striker Graeme Sharp flooring him, and Ratcliffe steamed forward to challenge Jones aggressively. Jones brushed his head forward in what appeared to be a headbutt, with Ratcliffe going down. Jones later claimed in his autobiography that his head barely touched Ratcliffe's and Ratcliffe had feigned contact to get him sent off, and expressed disappointment at the dishonesty of his fellow "hard man". This was later confirmed in Graeme Sharp's book, Sharpy, My Story when he admitted both him and Ratcliffe exaggerated Jones's contact on them both to get him sent off to their pleasure.
Ratcliffe has claimed in an interview the hardest (most aggressive) opponents he faced were Graeme Souness, Jimmy Case, Mick Harford and Billy Whitehurst, with Whitehurst supposedly being the hardest of all.
After leaving Everton in 1991, he went to Dundee and then played for a short spells with Cardiff City, Nottingham Forest and Derby County.
Ratcliffe was considered one of the fastest central defenders ever to play football.Everton he challenged the whole first team squad to a sprint race and won. Ratcliffe claimed that he challenged Linford Christie to a sprint in the street shortly after the 1992 Barcelona Olympics, in which Christie won the 100 m gold medal, and beat the runner. He was not the most skillful of footballers but he anticipated superbly, tackled ferociously and did the simple things well.
On arrival at
 International career
Ratcliffe was capped 59 times by Wales, often as captain. He also represented his country at under-21, youth and schoolboy level. Despite several near-misses and boasting famous players such as Ian Rush, Neville Southall and Mark Hughes as well as Ratcliffe, Wales failed to qualify for a major tournament while Ratcliffe was involved in the set-up. He was a room mate of Liverpool rival Ian Rush's during matches. Ratcliffe's last match for Wales in 1993 turned out to be Ryan Giggs's first.
 Management career
In 1994, Ratcliffe joined Chester City as assistant-manager to Mike Pejic and continued to play for a year. In the summer of 1995, he became manager of the Blues and stayed at the helm until August 1999, when he left after falling out with new owner Terry Smith. The highlight of his years at Chester City was guiding the club to the Division Three play-offs in 1996–97 and he later took credit for steering the club to a mid-table position in 1998–99 while in serious financial trouble. Reputedly Ratcliffe drew £5,000 from his own bank account to help cover the costs of a water bill because the club's cheques were refused.
In November 1999 Ratcliffe joined Shrewsbury Town as manager and helped them avoid relegation from the Football League on the final day of the 1999–2000 season at Chester City's expense. The highlight of his tenure was a January 2003 FA Cup third round victory over his old club Everton, who were doing well in the Premiership at the time. Interestingly, Everton manager David Moyes was a former Shrewsbury player. But a disastrous run after this saw Shrewsbury Town relegated to the Football Conference after 53 years in the Football League. Ratcliffe left the club within days, stating that he had to take the blame for Shrewsbury Town's downfall as he had brought in most of their players.