Siniaková became world No. 1 in doubles on 22 October 2018 and held the top ranking for the next 33 weeks. She has won 11 doubles titles on the WTA Tour, including 2 at WTA 1000 level. Siniaková reached her career-high singles ranking of world No. 31 in October 2018, and has won 2 WTA titles in singles, at the Shenzhen Open and Swedish Open in 2017. She was part of the Czech team which won the 2018 Fed Cup, and won an Olympic gold medal in women's doubles alongside Krejčíková at the 2020 Tokyo Olympics.