Briton Murray, on the comeback trail after hip surgery, was initially set to face Roger Federer in a blockbuster Group C clash in Sydney but the 20-times Grand Slam champion pulled out of the Jan. 3-12 tournament, making Switzerland ineligible.
Bulgaria have replaced Switzerland in the group, meaning Murray instead faces a prospective match with Dimitrov, dubbed "Baby Fed" for his similar playing style to the Swiss master.
Chile, Poland, Uruguay, Moldova and Norway are the other five teams that qualified for the 24-nation field at the close of the second and final deadline.
The six group winners and the two best second-placed finishers across the groups reach the ATP Cup Finals in Sydney.
Each tie comprises two singles and one doubles match.
World number one Rafa Nadal kicks off his tournament with Spain in Perth against Group B rivals Japan, Georgia and Uruguay, the tournament draw confirmed on Thursday.
Serbia, led by world number two Novak Djokovic, play Chile, France and South Africa in Group A in Brisbane.
Russian young gun Daniil Medvedev, beaten in the U.S. Open final by Nadal, will highlight Group D for Russia against the United States, Italy and Norway.
Group F has Germany, Greece, Canada and Australia playing off in Brisbane and boasts a mouthwatering array of young talent.
German world number six Alexander Zverev is likely to feature in the singles along with Greek tyro Stefanos Tsitsipas and tempestuous Australian Nick Kyrgios.
Group A - Serbia, France, South Africa, Chile (Brisbane)
Group B - Spain, Japan, Georgia, Uruguay (Perth)
Group C - Belgium, Great Britain, Bulgaria, Moldova (Sydney)
Group D - Russia, Italy, United States, Norway (Perth)
Group E - Austria, Croatia, Argentina, Poland (Sydney)
Group F - Germany, Greece, Canada, Australia (Brisbane)