Republic of Ireland winger Damien Duff has completed his £17m move to Chelsea.
The 24-year-old winger has signed a four-year deal and becomes the Blues' fourth high-profile summer capture following billionaire Roman Abramovich's takeover of the club.
Wayne Bridge also signed for the Stamford Bridge club on Monday to add to the earlier arrivals of Glen Johnson from West Ham and Geremi from Real Madrid.
The quartet have taken Chelsea's spending to the £37m mark.
Duff will now join the Chelsea squad for their Far East tour where they will be taking part in an inaugural FA Premier League Asia Cup in Malaysia, along with Premiership rivals Newcastle and Birmingham.
Duff had asked for the weekend to think over the move after discussions with Chelsea boss Claudio Ranieri last Saturday.
"It's been a tough weekend and a long one," Duff told Chelsea's in-house television station.
"And it was a tough decision because I didn't really want to leave Blackburn.
"I just want to get playing football now. I'm not interested in all this hullaballoo and just want to get playing football again."
"I've been down here three times in the last week and it feels right."
There were reports that Manchester United might try and hijack the deal after missing out on Ronaldinho.
But the Old Trafford club denied they were going to make such a move and Duff said that a switch to Old Trafford was never an option.
"The Man Utd stuff was speculation and it just came down to whether I wanted to stay at Blackburn or move to Chelsea," he said.
Duff now becomes the most expensive player in Chelsea's history, overtaking the £15m the club paid for striker Jimmy Floyd Hasselbaink.
Duff added: "It's a great honour for myself and my family but the most important thing is what happens on the pitch."
Blackburn finally agreed a fee from Chelsea on Thursday after turning down their previous offers.
Duff had a clause in his contract allowing him to leave if a club comes in with an offer of £17m.