Rothbart was born in Sarajevo, the capital of Bosnia and Herzegovina, which was at the time part of the former Yugoslavia. Due to the war, Robert and his family moved to Israel, where they stayed for two years before moving to the United States when he was eight years old.[1]
Although he initially committed to Indiana University, Rothbart decided in the summer of 2004 to skip college and play in Europe, where he's active today.
On August 17, 2017, Rothbart signed with Maccabi Kiryat Gat, joining his former head coach Roi Hagai.[7] In 35 games played for Kiryat Gat, he averaged 18.9 points, 12.3 rebounds, 2.3 assists and 2.1 blocks per game. Rothbart helped Kiryat Gat reach the Liga Leumit Finals, where they eventually lost to Hapoel Be'er Sheva.
On June 4, 2018, Rothbart returned to France for a second stint, signing a one-year deal with a second year option with ESSM Le Portel of the LNB Pro A league.[8] However, on November 11, Rothbart parted ways with Le Portel to join Hapoel Be'er Sheva for the rest of the season.[9]