Rijkaard was just 17, when Ajax coach Leo Beenhakker gave him his senior squad debut August 23, 1980. He made an immediate impact, scoring for his team 0–3 in the 2–4 away victory over Go Ahead Eagles, the first league match in the 1980–81 season. He would play another 23 games for Ajax in his first season, netting a total of 4 goals. In 1981–82 he won his first Dutch Eredivisie championship with Ajax, and went on to successfully defend that title in the following 1982-83 season. Rijkaard stayed at Ajax for seven and a half seasons, as a central defender (1981–82, 1982–83, 1984–85), a right midfielder and a central midfielder (1985–86). During this period he won the Dutch league championship three times (1981–82, 1982–83, 1984–85) and the Dutch Cup (KNVB-Cup 3 times (1982–83, 1985–86, 1986–87). In the 1986–87 season he won the European Cup II (Cup Winners’ Cup) with Ajax (Final: Ajax 1-0 Lokomotiv Leipzig). In September 1987, what would have been Rijkaard’s third season (1987–88) under Dutch football legend Johan Cruyff as head coach, Rijkaard stormed off the training field and vowed never to play under him again. He was signed by the Portuguese club Sporting CP, but he signed too late to be eligible to play in any competition. He was immediately loaned out to Spanish team Real Zaragoza, but upon completing his first season at Zaragoza, was signed by Italian side AC Milan.
Ajax return (1993–1995)
After five seasons in Italy, Rijkaard returned to Ajax in 1993. With Louis van Gaal at the helm, Rijkaard and Danny Blind formed the experienced defensive core of the Ajax team that won the first two of three consecutive Dutch Championships. Ajax were the unbeaten champions of the Netherlands in 1994–95 season and carried that success into Europe. In his final game, Rijkaard won the European Cup (which had been renamed as the Champions League) again, with a 1–0 victory over AC Milan in the 1995 final at the Ernst Happel Stadion in Vienna.