They are SooBeen Lee of South Korea, Jinzhu Li of China and Bohdan Luts of Ukraine.
In the finals, which will be held on Thursday, the three violinists will perform one of two concertos by Wieniawski, the Polish virtuoso after whom the competition is named: Violin Concerto No. 1 in F-sharp minor, Op. 14, or Violin Concerto No. 2 in D minor, Op. 22.
They will be accompanied by the Poznań Philharmonic under its music director Łukasz Borowicz.
The winner will be announced after Thursday's performances and will receive EUR 60,000 in prize money, along with a range of career-development opportunities.
These include international tours in South Korea, China, Taiwan, Italy and Brazil, as well as concerts in Poland.
Many special prizes will also be awarded, including the Charles Treger Special Prize, a EUR 10,000 award for the best performance of a Wieniawski concerto.
Treger won the Wieniawski Competition in 1962 and remains the first and only American to have claimed the event's top honour. The prize is endowed by his family.
The 10-member international jury is chaired by Polish violinist Bartłomiej Nizioł, who won the 1991 Wieniawski Competition. The panel also includes Andrea Obiso, Liviu Prunaru, Gerhard Schulz, Alexander Sitkovetsky, Akiko Suwanai, Agata Szymczewska, Vera Tsu Weiling, Sungsic Yang and Nancy Zhou.
The Wieniawski Competition is the world's oldest international violin competition, according to its organisers.
It was first held in Warsaw in 1935 and moved to Poznań after a 17-year hiatus. It has been held in Poznań since 1952, usually every five years.
Past winners have included David and Igor Oistrakh, Ida Haendel, Ginette Neveu, Agata Szymczewska, Veriko Tchumburidze and Hina Maeda.
Wieniawski was a child prodigy who entered the Paris Conservatory at age 8. He is widely regarded as one of the greatest violinists and composers of 19th-century violin music after Niccolò Paganini. He died in 1880 at age 45.
(mk/gs)