The Italian, who had led Inter Milan to three Italian championships in a row is expected to be in London tomorrow to finalise a four-year deal.
Mancini has been Chelsea-Mad's expected choice for several weeks.
With Grant sacked from the job on Saturday, events has escalated at a rapid rate.
Mancini is believed to have resigned from Inter allowing, again, as expected, Jose Mourinho to take over the the job.
Part of Mancini's appointment is to change the reputation of Chelsea and make them more "likeable" beyond the environs of SW6.
To that end, Chelsea are looking to bring back Gianfranco Zola to be Mancini's number two.
Zola - currently working with the Italian under-21 side in the Toulon tournament, will also act as Mancini's translator.