The employment status of 20,000 staff is unclear after huge debts and a pension deficit were announced.
And there are several major developments in Leeds that will be affected by the collapse.
East Leeds Orbital Road
The deadline for awarding the contract for the first phase of the £115million dual carriageway construction scheme was December 28, and Leeds City Council announced Carillion as the preferred bidder just before Christmas. However, they have now backtracked and insist the contract was never signed.The firm's biggest competitors, Balfour Beatty, were also shortlisted, but it could end up being put back out to tender.
The Homes and Communities Agency appointed Carillion to develop the Tower Works site in Holbeck back in 2015, but work never began. The plans are for the former pin factory - known for its landmark, Renaissance Italy-inspired listed chimneys - to be converted into a mix of office, leisure and residential space, which would make it a focal point of the South Bank development. Completion was scheduled for 2020.
There have been several delays and false starts since then, and the original plans have had to be amended to accommodate more rental properties. The HCA will likely have to submit yet another planning application once they have appointed a new contractor.
Although the two main segregated cycle routes have already been completed - the Leeds-Bradford stretch and a new eastern route to Seacroft - Carillion had been chosen by the council to carry out an additional £4million of work in the city centre.