Tournament director Colin Stubs had held the final spot in the field open until as late as possible, hoping to secure a top-10 player for the tournament that serves as warm up for the Australian Open.
Stubs had said earlier he had contacted representatives of the world's top four players, Novak Djokovic, Roger Federer, Andy Murray and Rafa Nadal, about filling the spot.
Djokovic instead chose to play Hopman Cup in Perth, the 31-year-old Federer has not played any competitive warmup matches this year as he manages his schedule to improve his longevity, Murray is in Brisbane, while Nadal withdrew from the Australian Open due to illness.
Berdych, however, who reached the quarter-finals in Chennai earlier this week, felt he needed more match practice and asked to join the Kooyong tournament, Stubs said in a statement on Sunday.
The 27-year-old Czech joins 2009 US Open champion Juan Martin del Potro, world number nine Janko Tipsarevic, top-20 players Juan Monaco, Milos Raonic and Japan's Kei Nishikori, Melbourne crowd favourite Marcos Baghdatis and former world number one Lleyton Hewitt in the January 9-12 tournament.
The event has traditionally attracted a high quality field as it guarantees players three competitive matches on the same surface used at the Australian Open a few kilometres down the road at Melbourne Park the following week.