Sykes went undrafted in 2015 but was immediately signed by the Cleveland Cavaliers within hours after the draft. He played in Cleveland for the 2015 Summer League. He was then invited to the San Antonio Spurs' training camp. Sykes played for San Antonio in three preseason games, and then spent the season playing for their D-League affiliate, the Austin Spurs.
During the summer of 2016, he played for the Golden State Warriors in the Las Vegas Summer League. After the Summer League, he was drafted 12th overall in the Korean Basketball League draft, and he decided to play there for Anyang KGC for the 2016-17 season. KGC would go on to win the league championship, despite Keifer going down with an ankle injury towards the end of the playoffs.
After a summer of limited NBA opportunities due to his lingering ankle injury, Keifer signed with Ankara DSi S.K. of the Turkish Basketball League, where he finished the season as the league's leading scorer at 23.1 points per game. He also averaged 3.8 rebounds and 4.8 assists, while shooting 50.6% from the field and 42.6% from behind the arc.
In January of 2019, Keifer stepped up to play for Sidigas Avellino of Italy's Premier Basketball League. After injuries to two of Sidigas Avellino’s key players, Sykes took over a leading role and boosted his game to another level, scoring 43 points, which is the new BCL scoring record. Later in 2019, Sykes moved on to the Chinese Basketball Association’s Guangzhou Long Lions, where Forbes magazine sports reporter, Chris Sheridan, referred to him as the “James Harden of China.” [link to article]
Since the spring of 2020, Sykes’ career has taken a unique path due to the COVID 19 pandemic. He played for three teams in four months. First playing with Turk Telekom (Turkish Basketball Super League), leading to the 2020 Basketball Champions League Final 8. Then another short term deal with Panathinaikos, a Greek Euroleague Team. Sykes is currently in Melbourne, Australia for the 2020-21 season of the NBL playing for the Southeast Melbourne Phoenix.
Anyone who has followed Keifer's career will undoubtedly note that his college team was the UW-Green Bay Phoenix.