Shepherd walked-off its £31m contract at the Fitzrovia hotel early last year following a series of payment rows.
Berners Hotel was placed into administration in August 2010 leaving Shepherd out of pocket for demolition and renovation work it had already completed
Caterer and Hotelkeeper reported that Shepherd had agreed to carry out demolition, structural alterations, extensions and fitting-out work at the hotel in 2008, but claimed interim payments were not made as they fell due.
The builder won an initial judgment in February 2010 for £1.18m, which remains unpaid.
Shepherd then agreed a deal with JJW in May 2010 for Berners to pay £4.5m in three instalments as full and final settlement of all claims, according to a High Court writ.
Despite JJW guaranteeing that Berners would make the payment, the money remains outstanding.
Now Shepherd is suing JJW for payment of £4.5m, plus VAT and interest, taking the total amount to more than £5m.
The hotel was due to reopen last year with 176 refurbished bedrooms, a new bar and restaurant, and ballroom.
Berners has since been sold to Marriott International for £60m.
It is now undergoing further renovation work and will open under the new Edition brand, designed by Ian Schrager, within two years.