I guess by league one you mean the division called Coca-Cola Football League One, the third highest division, after the Premier League and Championship. Chelsea never won it. Chelsea have won the Premier League 3 times, in 1955, 2005 and 2006, and the Championship twice, in 1984 and 1989.
Chelsea has one the Champions League only one time. They won their solitary champions league in the 2011-12 season.
One
Chelsea has won 3 times Manchester United has won 12 Arsenal has won 3 times Blackburn has one just once
helsea have won six national league titles, seven FA Cups, five League Cups andfourFA Community Shields, one UEFA Champions League, two UEFA Cup Winners' Cups, one UEFA Europa League and one UEFA Super Cup.
How many goals Ronaldo score against Chelsea at Manchester United
Chelsea have won four premier league titles, two second division titles, seven FA cups, four community shields, and one UEFA champions league titles.
Chelsea have won the E.P.L four times one in 1950, two under Mourinho and last year with Mario Anchelotti..
Barclays Premier League - England.
Manchester United, Chelsea, Arsenal and Blackburn
one
Chelsea have won the Premier League title on three occasions - in 2005, 2006 and 2010. Two of them was with Ex-Porto and Blues manager Jose Mourinho nicknamed 'The Special One' and other one was with 2-times Champions League winner with his former club AC Milan - Carlo Ancelotti. Since they won their third title, they have retained their FA Cup crown by winning their first Premier League & FA Cup double in their 105-year history.
Arsenal are not even in the league division one, so how can they win it...