During the 2018-19 season, Geisser recorded one assist in 41 regular season games with Hershey. The Stans, Switzerland, native was also selected to represent Switzerland at the 2019 World Junior Championship.
The Capitals selected the 6'4", 201-pound defenseman in the fourth round, 120th-overall, in the 2017 NHL Entry Draft. Prior to the draft, Geisser was ranked 30th overall among European skaters by NHL Central Scouting. With the Capitals' selection of Geisser, Washington had selected a Swiss-born player in the NHL Draft in three consecutive seasons (2016: Damien Riat, 2015: Jonas Siegenthaler).
Geisser made his National League debut in 2016-17 and recorded one assist in 14 games with EV Zug in his rookie season. In 52 career National League games, all with EV Zug, Geisser has seven points (2g, 5a).
In addition to his 2019 World Junior Championship selection, Geisser represented Switzerland at the 2017 IIHF World U18 Championship, the 2016 Ivan Hlinka Memorial Cup and the 2016 U20 4 Nations Tournament.
