After graduating from high school, Andriunaitis, moved to the U.S. and represented Southern Methodist University and SMU Mustangs[8] for four years.

Andriunaitis in the men's 400 m Medley relay, along with his teammates Matas Andriekus, Vaidotas Blažys, and Eimantas Vijaikis, posted a time of 3:50.97 and ended up in the 17th place beating six countries.

Also, Andriunaitis helped his team, made of Vytautas Janušaitis, Vaidotas Blažys, and Rimvydas Šalčius, to win 4x50 m Medley relay.

In the 2011 Conference USA Championships Andriunaitis, along with David Larsson, Mindaugas Sadauskas and Blaz Korosec, helped lead the 400-yard Freestyle relay to a first-place finish with an NCAA time of 2:56.37.

[21] In 2012 at the Conference USA Houston, Texas, Andriunaitis with Nicolai Hansen, Matt Roney, and Blaz Korosec touched the wall in 6:32.80 (NCAA B) and won the 800-yard Freestyle relay.

[22] At the 2012 Lithuanian National Championship, Andriunaitis represented Kauno Plaukimo Mokykla and took gold in the 4 × 100 m Medley relay.

[24] Andriunaitis placed 5th in the 50 m Freestyle just 0.16 of a second behind closest competitor, NCAA team member for Arizona State University - Tadas Duškinas.