Chelsea have splashed the cash in recent years but some of their best acquisitions have come through the free agent market
Chelsea's transfer strategy has faced criticism in recent years, with numerous high-profile signings struggling to deliver the expected impact. Prior to Liam Rosenior's appointment as head coach last month, the Blues had spent well over £300million in the summer with several of their big-money signings yet to show a return on their investment.
The likes of Liam Delap, Jamie Gittens, Jorrel Hato and Alejandro Garnacho have failed to consistently perform in a side whose expenditure warrants a Premier League title charge, yet that is not the reality for the west London club.
Despite the substantial spending under Clearlake Capital's ownership, Chelsea remain some distance from reclaiming their position at the summit of English football. With Rosenior in the early stages of his reign, there's scope for the Blues to strengthen their squad through free agents.
Here, Mirror Football examines some of the club's most triumphant free transfers....
Thiago Silva
Thiago Silva was secured by Frank Lampard's side on a free transfer following his exit from Paris Saint-Germain. He signed a one-year deal in 2020 and stayed at the Bridge until 2024.
The Brazilian, who had collected titles with AC Milan and PSG but never the Champions League, claimed the prestigious trophy in his maiden campaign with the Blues. Silva accumulated 155 appearances for Chelsea and became the first defender since John Terry in 2006 to be crowned the club's Player of the Year in 2023.
He departed at the conclusion of his contract last summer to return to Fluminense before signing with Porto last December to enjoy a second stint with the Portuguese giants.
Didier Drogba
Didier Drogba, amongst Chelsea's greatest ever strikers, arrived from Marseille in 2004 and amassed 10 trophies, including the unforgettable 2012 Champions League triumph sealed with his iconic header and decisive penalty.
Following a short spell in China with Shanghai Shenhua, he transferred to Galatasaray where he helped secure the Super Lig title before making an emotional return to Stamford Bridge in 2014. The Ivorian penned a one-year contract and claimed his fourth Premier League crown under Jose Mourinho.
Gus Poyet
After a seven-year stint at Real Zaragoza where he left the club as their longest-serving foreign player, Gus Poyet joined Chelsea as a free agent in 1997. The ex-midfielder had an injury-hit debut season as he tore his ACL but went on to become a reliable goalscorer for the next three years in west London.
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Accruing a total of 49 goals in 145 games, Poyet enjoyed a trophy-laden stint at the Blues, winning the FA Cup, UEFA Cup Winners' Cup, UEFA Super Cup and League Cup.
Samuel Eto'o
Another legendary striker who arrived on a free was Samuel Eto'o in 2013. Having been amongst the select few players who joined Russian outfit Anzhi Makhachkala, the Cameroon star linked up with Mourinho again on a one-year agreement.
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He signed after Chelsea's unsuccessful pursuit of Wayne Rooney, bringing with him a remarkable record of over 250 goals for the likes of Barcelona, Inter Milan and Mallorca. The forward found the net 12 times for the Blues, including a memorable hat-trick against Man United.
While Chelsea never witnessed Eto'o at his absolute peak, his time at the club was certainly entertaining.
Ruud Gullit
In the 16 years Ruud Gullit was a professional footballer before his 1995 move to Chelsea on a free, the legendary Dutchman was part of one of the greatest club dynasties in sport during his time at AC Milan.
The 1987 Ballon d'Or winner may have been in the twilight years of his career while at Stamford Bridge but his consistent performances meant he finished runner-up to Eric Cantona for the Football Writers' Association (FWA) Footballer of the Year award in his debut season.
Gullit also became Chelsea's player/manager in his last two seasons at the club as he guided them to FA Cup glory in 1997 - their first major trophy in 26 years.
Michael Ballack
Michael Ballack made the switch to Chelsea after his Bayern Munich contract expired, turning down approaches from Manchester United, Real Madrid, Inter Milan and AC Milan. His choice to join Stamford Bridge was swayed by Robert Huth and Jens Lehmann.
Having collected three Bundesliga titles with Bayern, the midfielder arrived to vie with Frank Lampard, Claude Makelele and Michael Essien for a place in Mourinho's midfield. Throughout his four-year spell in the capital, Ballack secured three FA Cups, a Premier League title and the League Cup, racking up over 160 appearances.
He departed Stamford Bridge in 2010 before calling time on his playing career in 2012.
Gianluca Vialli
Gianluca Vialli, who tragically passed away in 2023, enjoyed a glittering 16-year career in his homeland where he turned out for Cremonese, Sampdoria and Juventus. It was after Vialli's four-year stint in Turin that he opted to go abroad for the first time to join the Blues in 1996 on a free transfer.
The former forward spent the last three years of his career in west London and scored an impressive 40 goals in 88 games. He'd won 11 major honours before his move to the Premier League and added three more pieces of silverware at Stamford Bridge as he won the FA Cup, League Cup and UEFA Cup Winners' Cup.