"Additional investments" have seen the bill rise from a projected £14 million to £21 million, a Glasgow 2014 spokesman said.
It comes as plans to demolish several tower blocks as part of the opening ceremony continue to attract controversy.
Games organisers revealed last week that five of the six remaining Red Road blocks of flats will be blown up on July 23, and the footage beamed live into the ceremony at Celtic Park.
But thousands have signed an online petition put forward by former Socialist MSP Carolyn Leckie, urging Sports Minister Shona Robison and Glasgow City Council not to make the demolition of the tower blocks part of the high-profile opening event.
A Glasgow 2014 spokesman said today: "The opening and closing ceremonies are key moments of the Games, when the eyes of the world will be on Glasgow and Scotland.
"They offer a unique opportunity to showcase the host nation, the host city and the talent of the Scottish people. As we have developed the ceremonies, opportunities have arisen to add to the spectacle to deliver truly memorable events.
"To make the most of this once-in-a-lifetime opportunity, we have chosen to make some additional investments in the ceremonies."
The content of the opening ceremony is expected to be agreed by May, while the closing ceremony is expected to be "music-focused and have a party atmosphere", according to minutes of the most recent meeting of the Glasgow 2014 strategic group in February.
It states: "Ty Speer (Glasgow 2014 deputy chief executive) provided a presentation on ceremonies, which covered the creative content, progress with programme management and risks, and an update on the budget.
"The run of show for the opening ceremony had been agreed and that development of the detail was now under way. The content of the opening ceremony is likely to be tied down by May.
"After discussion, the meeting agreed that the OC (organising committee) should assess whether additional budget should be transferred to ceremonies and sport presentation, and present options to the budget oversight group so that a recommendation can be given to the next strategic group meeting.
"Ty reassured the group that plans for the closing ceremony were progressing well, and that the closing ceremony would be music-focused and have a 'party' atmosphere."