Planning permission for the 40m-high lights was unanimously approved at a Leicester City Council meeting on Wednesday evening.
Chief executive Wasim Khan said: "It is fantastic news.
"We saw an average 48% increase in attendances for NatWest T20 Blast matches in 2015. The floodlights will help retain and grow our audiences."
The club hope to have to the floodlights installed for the first T20 Blast game of the season in May.
Mr Khan added: "We can start games later in the evening which will give more people the opportunity to attend after work."
Leicestershire say approval for six floodlights at Grace Road will improve attendances and increase revenue.