Sedney started competing in Athletics at the age of eight at the track and field club ARV Ilion in Zoetermeer.

[3] A year later she competed at the 2012 World Junior Championships in Barcelona, placing sixth in the 4 x 100 meters relay with the Dutch team (Schagen, Sedney, Miquella Lobo and Marloes Duijn).

[4] In 2013 she won bronze with the Dutch relay team (Schagen, Sedney, Van Agt and Eefje Boons) at the European Junior Championships in Rieti.

At the European U23 Championships she finished fourth in both the 100 metres with a time of 11,62 and the relay with the Dutch team (Schagen, Van Agt, Sedney and Boons).

The Dutch 4 × 100 meters relay team (Visser, Dafne Schippers, Sedney and Jamile Samuel) finished fifth in 42.32, but was disqualified for a changeover infringement.

In 2019 at the 2019 World Championships in Doha was part of the Dutch 4 x 100 metres Relay Team (Nargélis Statia Pieter, Van Hunenstijn, Samuel, Sedney).