On the professional club level, De Boer played for Ajax (1988–91 and 1993–99), Twente (1991–93), Barcelona (1999–2000), Rangers (2000–04), Al-Rayyan (2004–05) and Al-Shamal (2005–08).

After two seasons at Twente from 1991 to 1993, he returned to Ajax under manager Louis van Gaal, and had his most successful spell as a player, winning three consecutive Eredivisie titles in 1993–94, 1994–95 and 1995–96.

Ajax, however, apparently backed down on that agreement after floating the club on the stock market and pledging to shareholders that it would hold both of the De Boers and build around them a team to recapture the UEFA Champions League.

In January 1999, Frank and Ronald signed for Barcelona for £22 million, joining their former Ajax manager Louis van Gaal at the Camp Nou.

[4] While De Boer was impressive at Ajax during the 1990s and for the Netherlands up to and including the 1998 FIFA World Cup, his high-profile transfer to Barcelona in January 1999 marked what would be an unlikely bad patch for a prolific goal-scoring midfielder, as he managed to feature in only 33 La Liga games for the club and scored just one goal in La Liga.

[5] Among the Dutch internationals who at that time played for Rangers were Bert Konterman, Arthur Numan, Fernando Ricksen and Giovanni van Bronckhorst.

In the Dutch national team, De Boer was used in various positions, including right-half, centre forward and attacking midfielder.