Ms Mardini had to swim for hours after capsizing in the Mediterranean with her sister. They saved 20 people who eventually reached the Greek island of Lesbos.
Granted refugee status by Germany, she swam at the Games last August as one of 10 athletes in the first-ever refugee Olympic team which she hopes will become a permanent fixture.
"I am grateful for this opportunity and platform to tell the world that whilst we are young ... we have already experienced horrors, loved and lost homes, friends and family as if we have lived 100 years," Ms Mardini told a news conference on Thursday.
Ms Mardini, 19, is still studying in Berlin, continuing her swimming training two to three hours a day and learning German, but will go soon on a UNHCR mission to Tokyo, venue of the 2020 Summer Games.
UN Deputy High Commissioner for Refugees Kelly Clements said plans for that were not finalised.
Ms Mardini, whose appearance in Rio served to highlight the refugee crisis to a global audience, said in her new role she wanted to show people, "that refugees are actually humans and normal people also, who can do a lot of things like them."
(Reporting by Stephanie Nebehay, Editing by Robin Pomeroy)