He was a member of Costa Rica’s youth national teams, playing in the 1995 FIFA World Youth Championship finals in the Qatar.

Born in Heredia, Wanchope began his career with CS Herediano moving to England to play with Derby County along with fellow Costa Rican Mauricio Solís on 27 March 1997. He cost Derby £600,000.

After scoring 28 goals in 83 games within 2 seasons for Derby, Wanchope was sold to West Ham United for £3.5 million on 16 July 1999.

Wanchope made his debut for West Ham on 28 July 1999, at Upton Park, against Heerenveen in the Intertoto Cup. His first West Ham goal came on 4 August 1999 in the away leg of the same tie. He scored 15 goals in 47 appearances in all competitions; his final game coming on 14 May 2000, at home to Leeds United. During his one year at Upton Park Wanchope formed a deadly partnership with Paolo Di Canio, the two scored a combined 31 league goals in the 1999–2000 season, and West Ham finished 9th in the Premier League, putting them in the top nine for the third consecutive season. He was eventually sold to Manchester City at the start of the 2000–01 season, following the arrivals of Davor Šuker and Frédéric Kanouté, for a fee of £3.65million.

On 23 August 2000 he scored a hat-trick in a 4–2 win against Sunderland. Wanchope earned a starting position at Manchester City, but was unable to help them avoid immediate relegation back to Division One at the end of the 2000–01 season, despite scoring nine league goals.

Wanchope would become hugely important to the senior Costa Rica national team, after making his debut in an October 1996 friendly match against Venezuela and playing for the team in the 2002 FIFA World Cup and several Gold Cups. On 8 October 2005, Wanchope became the all-time leading goal scorer for Los Ticos when he scored the first goal in a home win over the USA in the qualifying match that sent Los Ticos to the 2006 FIFA World Cup. Wanchope has twenty plus World Cup qualifier goals to his name.

In August 2004, Wanchope was sold to Málaga CF of the Spanish La Liga for £500,000. He played 25 games for the club, scoring 6 goals.

In 2005, ESPN declared Wanchope’s goal against Numancia the best of the entire 2004/05 Spanish First Division. In 2006, following the World Cup in Germany and short but successful stints with Al-Gharafa in Qatar and Herediano in his native Costa Rica, he signed with Argentine club Rosario Central., scoring 5 goals in 14 games.

On 29 December 2006, J1 League club FC Tokyo announced the acquisition of Wanchope on a transfer from Rosario Central. Along with local prospect Sota Hirayama, Wanchope allowed FC Tokyo to utilise a pair of large (190 cm+) strikers. He was released by FC Tokyo and subsequently signed a one-year deal with MLS team Chicago Fire.

On 9 June 2006, he scored twice in the opening game of the 2006 World Cup, a 4–2 loss to Germany. These two goals made Wanchope the inaugural Costa Rican to score twice in one World Cup match, and put him alongside Rónald Gómez as the sole Costa Ricans ever to score more than one World Cup goal. After the defeat to Germany, Costa Rica were defeated by both Ecuador and Poland. Thus Costa Rica finished last in their group and failed to qualify for the second round. Wanchope played his last game for his country in January 2008 when Sweden had come to visit Costa Rica. He played 25 minutes and then he was substituted.

On 16 November 2007, after a 13-year career in football, Wanchope decided to put an end to his career, primarily based on how his old knee injury was affecting his performance on the field, the same injury that made him lose large parts of his career with Manchester City, making him unable to reach his best physical shape, an argument that was commonly criticized by the press during recent years in every club he played for. At his retirement press conference he manifested his interest in becoming a professional coach, looking forward to accomplishing it in England.

In September 2014, he won the Copa Centroamericana with the Costa Rica national football team. On January 31, 2015, he was officially named as national team coach.

On 12 August 2015, Wanchope resigned as manager of Costa Rica’s national team following a post-match brawl with a steward.