Transgender K Prithika Yashini and 21 other transgenders were appointed as Sub-inspectors of police by City Police Commissioner Smith Saran after undergoing medical check-up on Monday.
The candidates will train in Chennai, police said.
But Yamini had to fight for her rights.
Yashini had appealed the Madras High Court after her application was rejected by the Tamil Nadu Uniformed Services Recruitment Board (TNUSRB) last year.
In November, 2015 the Madras High Court had directed the TNUSRB to appoint her as SI and also ordered it to include transgender as third category.
“I will help transgenders get education and employment ,and take action against those involved in child abuse and sexual harassment,” she said.