The group is to spend £500m on redeveloping the street over the next ten years and is looking for an agency to communicate these changes to the planning authority, Westminster City Council, as well as tenants.
Crown Estates deputy head of communications Giles French said it is hoped the review will be concluded by late spring.
The current Regent Street account is held by PPS. This latest review will not affect the group-wide lobbying business, currently held by Weber Shandwick, or its PR account, held by The Communication Group.
Regent Street was the subject of an audit on its future last year. Options for its long-term future to arise from the audit included a traffic calming scheme and the possibility of pedestrianising the street.
An electric transport system for the street has also been mooted.
The Crown Estate includes a vast portfolio of 120,000 hectares of farmland, 12 miles of coastline, as well urban areas also including Regent's and St James's parks.
Despite being owned by the Queen, the estates are hereditary possessions and have been passed on since the reign of King Edward the Confessor.
All profits go to the Treasury. Latest figures for year ending 2002 put the estate's profits at £163.3m.