The Big Yin was to play seven nights at the city's SECC in October, with sell-out dates on October 19, 20, 22, 23, 24, 26 and 27.
Connolly will now also play on October 31.
The tour, which starts on September 29 in Aberdeen, sold out its first two shows at the 2600- seat Aberdeen Music Hall in less than an hour, with people queuing outside the venue from around 4am to buy tickets.
The High Horse is Connolly's first Scottish tour in five years and comes after he was given the all-clear following surgery for prostate cancer last year.
At 71, the comedian has vowed to continue acting in films and on stage, despite suffering from Parkinson's disease. He has been using notebooks and crosswords to train his memory.
Tickets for the new date go on sale at 11am on Monday, priced £31.40-£33.60. For details, visit www.ticketsoup.com.