The 19-year-old singer, who is the ambassador for the organisation since 2009, recently filmed an emotional appeal for Sahel region, where a severe drought has left many families without food, reported Contactmusic.
Gomez has now pledged to limit her spending in a bid to experience how poorer families live.
"In a continued effort to help support Sahel...I am living off of 1.50 a day (this week). 1.4 Billion people live on USD 1.50 per day their whole lives, we only need to do it for one week. Can you do it? Join Unicef... In the Live Below the Line Campaign and help provide children food and supplies to the drought effect region of the Sahel," she wrote on her Facebook page.