The DMK has elected former Deputy Chief Minister Udhayanidhi Stalin as the legislature party leader in the House.
Party sources said on Sunday that former DMK minister and senior leader KN Nehru has been chosen as the deputy legislature party leader.
In addition, former DMK minister E V Velu has been elected as the party whip.
The DMK has 59 MLAs and will function as the principal opposition in the House. The Tamil Nadu Assembly has 234 members.
Although TVK on its own did not secure the majority in the 234-member Tamil Nadu Assembly, Joseph C Vijay managed to get support from the Congress, VCK, CPI, CPI (M) and IUML to gather 120 MLAs and cross the 118 majority mark to form the government.