Christiaens started his youth career at Ruiselede before moving on to Deinze and eventually Club Brugge.
[2] Towards the end of the 2010–11 season, he was released by Club Brugge and signed for Belgian Third Division side Torhout.
[3] He made his senior debut on 17 August 2011 in the 1–1 home draw against Géants Athois, coming on as a substitute in 80th minute.
[5] On 19 November 2011, he made an appearance for Filipino side Global FC in a round of 16 match in the 2011 United Football Cup against the Philippine Army.
[11] Christiaens in particular was able to impress sufficiently that he was also named in the senior national team's 20-man squad for the 2011 Long Teng Cup.