Charlton boss Alan Curbishley told the club’s official website: “I would like to thank Jose Mourinho for allowing Alexei to join us on a season-long loan deal.
“The player wanted to come to us and we are very pleased to welcome him to the club.
“Alexei is a flexible player and can play in so many positions. He gives us extra options and makes our squad that much bigger.”
Smertin has joined The Addicks in the hope of securing first team football, and to aid his chances of making Russia’s 2006 World Cup squad.
“I decided I needed match practice week in and week out. That will be better for me and for the Russia national team,” he said.
“No training, regardless of its quality — and Chelsea training was of the highest quality — can compare with playing competitively.”
There is still a chance that Smertin could appear in a Chelsea shirt again before the end of the season.
“When I told Jose Mourinho I wanted to leave he was surprised,” Smertin admitted.
“He told me he still counts on me and that Chelsea have a long season in front of them, and we decided that if something goes wrong for me at Charlton I will be able to rejoin the Blues.
“He said that they would be waiting for me.”