Cookie Time says the experience is highly sought after by future employers.
Founded in 1983, Cookie Time Limited is an entrepreneurial, innovation-led food company.
Based in New Zealand, the company is focused on international licensing opportunities.
Ms Barrett said: "As a second-year law and commerce student at the University of Canterbury, the Christmas Cookies job really struck me as a business opportunity where I could develop key business skills that will set me apart in the workforce. Working to targets is a motivating factor to maximise my sales and to help pay off my student loan."
Competition for a place on this year's selling team was especially fierce, with a record number of applicants for the fourth year running. More than 750 university students applied for just 73 places.
Each seller is allocated a geographic territory (73 from the far north to the deep south) and operates as an independent business over the seven weeks of the campaign, helping to fund their studies while learning business management and operational skills.
Christmas Cookies are bite-sized cookies made from a special Christmas recipe and packaged in a 600g re-useable bucket.
Cookie Time was voted best New Zealand owned business by the grocery industry earlier this year.
Part of the proceeds from this year's Christmas Cookies campaign will go to the Cookie Time Charitable Trust, which has raised more than $1.4 million to date. This year a $50,000 donation will be made to the trust, which is dedicated to helping Kiwi kids discover their gifts.
As principal sponsor of the Dyslexia Foundation of New Zealand, the trust's work has made a significant difference to the one in 10 New Zealanders who have dyslexia, particularly in supporting children to reach their full potential.