The head girl of Esperance Senior High School placed second in the state finals of the Plain English Speaking Awards.
The state finals were held in Perth on June 15.
Anna Smith delivered a powerful speech entitled 'No Minor Issue' on child marriage.
The speech was slightly modified from Anna's winning address at the semi finals.
Anna said the prepared speech went really well, but her timing was a slightly off, which ultimately stopped her from going through to the national contest.
After previously struggling to deliver an impromptu talk, Anna said she "smashed it" and achieved first place at the finals.
"I was so happy after I pretty much flunked it last time, I was stoked," she said.
"I spoke about my family as my sister has Type 1 diabetes.
"The topic that we were given was 'the best things in life are free'. It was a an area that the judges hadn't really thought of because everyone else talked about love and how you can give love for free.
"I spoke about how the Australian Government pays for my sister's pump and all her medical supplies."
Anna hopes to study neuroscience at university and aims to one day speak about her research,.
"I am a very outgoing person and I love to talk to people," she said.
"In the future I'd like to give speeches about my studies, and to deliver that, I need to have good public speaking skills."
Anna was the first student from regional WA to enter the awards and said she hoped more schools in country areas would get involved.
English head of department Vicky Williams said she was proud of how well Anna represented herself and the school.
"I'm very pleased that the effort she has put in, on weekends, before school and during her study periods has paid off," she said
Ms Williams said public speaking was a skill that always needed development.
She said the awards were beneficial to all students in allowing them to see what can be achieved through public speaking.
Anna was the only student in the WA state finals from a government school.
"To get so far to the state finals and to come second is a kudos to public education," Ms Williams said.