Waja, 21, spent his entire career with WAFA SC where he made 59 appearances in the Ghana Premier League, scoring five goals. Waja captained the side to a second place finish during the 2016-2017 season.
To date, Waja has made two appearances for the Ghanaian National team, making his debut on May 25, 2017, in a friendly against Benin. Waja was called in for two FIFA World Cup qualifying matches against Congo in September 2017 but was an unused substitute in both matches. Waja has also represented Ghana at the U-17 level.