Belarus has been rocked by large-scale protests since the presidential election in early August, with the opposition claiming the outcome of the vote was rigged.
"Dear friends! I, Maria Kolesnikova, and members of Viktor Babariko's headquarters today announce the creation of political party 'Together", the statement says.
The election on 9 August saw the incumbent president Alexander Lukashenko re-elected to a sixth term with over 80 percent of the popular vote. The opposition was coalesced around unlikely contender Tikhanovskaya.