The 20-year-old centre-back has penned a three-and-a-half-year deal at the Reebok Stadium.
A product of the Foxes’ youth system, Bolger made 52 appearances across three separate loan spells with Bristol Rovers over the past three seasons.
Wanderers manager Dougie Freedman revealed the Irish youngster will not be an immediate first-team fixture.
He said: “Although he’ll train with the first-team squad, Cian is one who will initially play in the development squad.
“We believe he has the potential to be knocking on the door for a regular place in the senior team in the near future.”
A goal apiece from James Tomkins and Luka Milivojevic handed Crystal Palace a crucial 2-0 win over Huddersfield at the John Smith's Stadium on Saturday evening.
Manchester United bounced back from their Champions League exit as they beat Brighton 2-0 at Old Trafford on Saturday night to reach the FA Cup semi-finals.
Tottenham reached the FA Cup semi-finals after they cruised to a 3-0 victory over Swansea in their quarter-final clash at the Liberty Stadium on Saturday.
Premier League basement club West Brom squandered the lead as they suffered a 2-1 defeat to Bournemouth at the Vitality Stadium on Saturday.
Chesterfield boss Jack Lester felt his side were unlucky not to claim all three points after their 1-1 draw at Cheltenham.