The 2003 Northern Arizona Lumberjacks football team was an American football team that represented Northern Arizona University (NAU) as a member of the Big Sky Conference (Big Sky) during the 2003 NCAA Division I-AA football season.

In their sixth year under head coach Jerome Souers, the Lumberjacks compiled a 9–4 record (5–2 against conference opponents), outscored opponents by a total of 409 to 305, and finished in a three-way tie for the Big Sky championship.

[1] The Lumberjacks were invited to play in the 2003 NCAA Division I-AA playoffs and defeated No.

1 McNeese State on the road in Lake Charles, Louisiana.

The team played its home games at the J. Lawrence Walkup Skydome, commonly known as the Walkup Skydome, in Flagstaff, Arizona.