In 2011, Papaconstantinou adopted the production pseudonymAlex P and started collaborating with record producer RedOne, joined RedOne's production and 2101 Songs writing team. This collaboration lasted three years until 2014, during which time he co-wrote and co-produced the Enrique Iglesias hit song "I Like How It Feels" and co-wrote and co-produced the Khaled album C'est la vie.[2][3] In 2013, singer Marc Anthony covered the Khaled song "C'est la vie" as a salsa tune titled "Vivir Mi Vida" ("Live My Life") for his studio album 3.0.[4] This version won a Latin Grammy Award in 2013 for Record of the Year and holds the record for the second-longest run inside the top-five in the Billboard Latin Songs, with 51 weeks.[5][6] During his collaboration with RedOne, Alex P co-wrote or produced multiple hit singles leading to 3 BMI Awards and a Latin Grammy Award.[7][8]
In 2017, Papaconstantinou co-founded and became a member of the music trio VAX, along with singer Teddy Sky and guitarist Viktor Svensson.[5] VAX released the song "6 in the Morning" featuring the Polish singer-songwriter Margaret followed by "Fireproof" featuring band lead singer Teddy Sky.