After going undrafted in the 2013 NBA draft, Armstead signed his first professional contract in August 2013, with the Slovenian Basket League's Krka Novo Mesto for the 2013–14 season.
[4] On December 25, 2015, he parted ways with AEK,[5] and signed with İstanbul BB of Turkey for the rest of the season.
[6] On 25 August 2016, Armstead signed with Turkish club Yeşilgiresun Belediye for the 2016–17 BSL season.
[8] In late October 2017, he left Neptūnas and signed with Greek club Rethymno Cretan Kings.
[9] Armstead spent the 2020–21 season with Fribourg Olympic of the Swiss Basketball League, averaging 14.2 points, 4.7 assists, 1.8 steals and 1.7 rebounds per game.