Trade unions claimed ministers were trying to make it easier for firms to sack people while business chiefs praised the move as a welcome simplification of the redundancy rules.
The changes were unveiled by Jo Swinson, the Employment Relations Minister, who stressed a consultation had produced a strong argument for shortening the period.
She said: "The process is usually completed well within the existing 90-day minimum period, which can cause unnecessary delays for restructuring and make it difficult for those affected to get new jobs quickly."
The LibDem MP for East Dunbartonshire added: "Our reforms will strike an appropriate balance between making sure employees are engaged in decisions about their future and allowing employers greater certainty and flexibility to take necessary steps to restructure."
Firms planning to make at least 100 redundancies have had to consult with employees, usually through trades unions, for 90 days – a process which has been in place for years.
The trades union leadership condemned the Coalition's move. Brendan Barber, General Secretary of the TUC, said: "The last thing we need is for the Government to make it easier to sack people."
Ian Murray, shadow employment relations minister, said: "David Cameron should be making it easier to hire, not easier to fire. We need a plan for jobs, not an attack on people's rights at work."
Eilidh Whiteford, the SNP's work and pensions spokeswoman, said: "The bizarre claim from Jo Swinson that this measure is aimed at helping workers epitomises the Scrooge attitude at the heart of the London Government."
However, the CBI said it had called for a simplification and streamlining of the collective redundancy rules and added: "The announcement is a welcome move in that direction."