Born in Accra to Ghanaian parents, Essien began his career in a local club in his native Ghana, called Liberty Professionals FC. He broke through when he played in the 1999 FIFA U-17 World Championship in New Zealand. This led to considerable attention from European scouts.

In July 2000, French club SC Bastia signed Essien. At Bastia, he did not command a regular place in the team, playing at right back, left back and in central defense. Then because of an injury to one of his teammates, he was given a temporary opportunity to play in central midfield. Essien flourished in this new role. Soon he was compared to Frenchman Patrick Vieira because of his ability to go from box to box. In 2002/2003 season he helped Bastia qualify for the UEFA Cup. He scored six goals that season. He became physically stronger and a harder tackler. Soon Paris Saint-Germain, Olympique Lyonnais and Olympique de Marseille made offers for him. He was not only popular in France, but also in England. Both major Merseyside teams, Liverpool and Everton, made offers for him.

PSG made the best offer and Bastia accepted it, but Essien rejected the contract, and instead agreed terms with Lyon. At Lyon, Essien played a more defensive midfield role, featuring regularly in the Lyon team that won the third and fourth of their current string of six consecutive Ligue 1 titles. He was also voted the 2005 Player of the Year by France's National Union of Professional Footballers (UNFP).

In August 2005, Essien declared that he would "go on strike" against Lyon because of the club's refusal to accept a transfer bid for him from English Premiership champions Chelsea. It was announced on 14 August that Lyon and Chelsea had agreed a £26m fee for the Ghanaian, finally ending one of the longest running transfer sagas in recent English football history. Essien is now Chelsea's second most expensive signing after the club signed Ukraine forward and captain Andriy Shevchenko from A.C. Milan on 22 May 2006.

The transfer went through on 19 August, purportedly for a slightly reduced fee of £24.4m nevertheless breaking Chelsea's previous record transfer fee, which they achieved the previous season by paying £24m for Olympique Marseille's Didier Drogba. He made his debut against Arsenal F.C. on August 21, wearing the number 5 on his shirt. He soon cemented his place in José Mourinho's side, starting the majority of the league games since his debut. He made an assist in his full debut against West Bromwich Albion F.C., and he replaced the injured Claude Makélélé in the defensive midfield role against Sunderland A.F.C. in the 2–0 win on September 10, 2005. The Chelsea midfield looks to have been strengthened by the powerful, athletic Essien, who could well form part of the Chelsea midfield with Frank Lampard for years to come.

On 15 December, he was handed a 2-match ban by UEFA for a controversial tackle on Dietmar Hamann, which resulted in his suspension from Chelsea's UEFA Champions League second round tie with eventual European champions F.C. Barcelona. Chelsea lost the two-legged tie, 3–2 on aggregate. Essien apologised to Hamann for the challenge (Hamann publicly accepted the apology) and insists that while he desires to be perceived as a player who 'unsettles' opponents, he is not a malicious or unsporting player. In January 2006, Essien was himself stretchered off the field, the victim of a poor challenge from West Ham United captain Nigel Reo-Coker, which sidelined him for three weeks.

Essien scored his first goal for Chelsea in March 2006, in a 2–1 victory over Tottenham Hotspur. His second goal came on 17 April 2006 against Everton with a powerful strike after an assertive burst through the defensive line. Essien ended his debut season in England with two goals, both in the Premier League. However, the arrival of midfielders Michael Ballack from Bayern München and John Obi Mikel from Lyn Oslo brought stiffer competition for places at Chelsea.

On September 12, 2006, Essien scored his first UEFA Champions League goal for Chelsea in a 2–0 victory over Werder Bremen of Germany. Undeniably his most memorable strike for Chelsea was the powerful, curling equalizer against Arsenal on December 10, 2006 from approximately 35 yards. The spectacular strike sent the home crowd into uproar. The match ended in a 1–1 draw, with Essien receiving the Man of the Match. Later in the same season Essien scored an equally dramatic late winner in the Champions League quarter-final against Valencia at the Mestalla. Running down the wing from his position at right-back he smashed an effort past Santiago Cañizares' at his near post to send Chelsea through to the semi-finals with a 1–2 victory on the night, and 2–3 win on aggregate. It was his first match back in the team after several weeks out with a knee injury. Later in a post-match interview, when asked how he felt about the win, he said he thought his team deserved the three points, despite it being a European Semi-Final.

On 15 May 2007, Essien was voted as Chelsea Player of the Year for the 2006–07 Season by the fans, becoming the first African to receive the honour. His goal against Arsenal was also voted as Chelsea Goal of the Season 2006–07.

His transfer from Olympique Lyonnais to Chelsea in August 2005 is one of those about which the Stevens inquiry report in June 2007 expressed concerns because of the lack of co-operation from agents Pinhas Zahavi and Barry Silkman.

On August 13, 2007, Essien grabbed the winner with his first goal of the 2007–08 Premier League campaign, as Chelsea defeated Birmingham City, to set an English record for unbeaten league matches at home – eclipsing Liverpool's previous top-flight record of 63, which Bob Paisley's team set between 1978 and 1981.

Essien was nominated for the 2006 FIFA World Player of the Year Award on October 12, 2006. One week later, he was nominated for the 2006 Ballon d'Or. He was also nominated for the 2005 FIFA World Player of the Year Award as well. He placed 22nd in 2005 and 22nd in 2006 in the FIFA World Player of the Year awards. He was voted as the 3rd Best African Footballer of the Year in 2006, a feat he achieved in 2005 as well. He won the 2006 BBC African footballer of the year award. Essien recently renewed his contract with Chelsea until 2012.

On October 10, 2007, he was nominated for the prestigious 2007 FIFA World Player of the Year Award for the third consecutive year and on October 21, 2007 Essien was also nominated for the 2007 Ballon d'Or Award for the third consecutive year as well.

--Wikipedia