Berasategui won a total of 14 top-level singles titles and 1 tour doubles titles. He won at least 1 singles title for 6 consecutive years (1993–1998). He began playing tennis at age seven and was the European junior champion in 1991. He turned professional later that year, and won his first top-level singles title in 1993, 2 years later. He reached a career-high singles ranking of world No. 7.
In 1994, Berasategui reached nine finals, winning seven of them. He also reached his first Grand Slam final at the French Open, where he faced fellow Spaniard and defending champion Sergi Bruguera. He was defeated in four sets, 3–6, 5–7, 6–2, 1–6.
Berasategui retired from the professional tour in May 2001, having had persistent wrist injuries since his match with Hernán Gumy at the Bologna tournament in June 1998. The injuries had an adverse effect on his results and form, and had caused his consistency and ranking to decline. He also suffered severe cramps of unknown origin in long matches.
Bererasategui was known for his extreme western grip, known as the "Hawaiian grip", where his unusual hold on the racket would allow him to hit both forehands and backhands with the same side of the racket. This helped him on clay, but he did not have much of an impact on other surfaces except for a quarterfinals appearance at the 1998 Australian Open, in which he beat world No. 2, Patrick Rafter, in the third round in four sets, and came back from two sets down to beat the 1995, 2000, and 2001Australian Open champion, former and future world No. 1 Andre Agassi in the fourth round. He lost in quarterfinals to Marcelo Ríos after winning a tight first set tiebreak 7–6(8–6), 4–6, 4–6, 0–6.