Edith Smith signed up at Grantham Police Station and her initial duties were to deal with prostitutes, female witnesses and children.
She was appointed after Grantham's watch committee and town council gave permission and underwent three weeks training in London to prepare her for the post.
Edith (1880 - 1924) wrote many reports about her work, including one in which she explained how she befriended the town's 'bad girls' and visited them in theatres and cinemas to persuade them not to ply their trade.
She said: "I received nothing but courtesy and co-operation from the managements as soon as I made my methods known and they realised I was there to act as a deterrent to their houses being used by prostitutes as a hunting ground and to look after frivolous girls likely to get into mischief.”
She cautioned 100 working girls during her first year in office.
She stayed in post until 1918 and the end of World War 1, then went to be matron of a local nursing home. She died in 1924 of an overdose of morphine.
The centenary was marked by a conference for women police officers, where Home Secretary Theresa May praised Edith's pioneering position as well as the job carried out by women officers today.