She was a good administrator and courageous general, She had diplomatically dealt with the mughal army and avoided a defeat. She defeated and brought King Ravivarma of Trivancore under her control. She had successfully defeated the Mysore invador brought Trichy and Tanjore under her control.

Rani Mangammal donated lands to Muslims, Brahmins and she also patronized Christians. She built many irrigational tanks for the development of agriculture. Rani Mangammal successfully completed many public works, like digging wells, and canals, laying roads, building choultries, mandapams, temples, planting trees on both sides of the road. The Mangammal choultry in Madurai is the good example of art and architecture of Rani Mangammal.