In 2010, two years after her debut, IU donated all the proceeds from her duet song with actor Yoo Seung-ho, while in 2011, she donated the proceeds from her fan meeting. In 2012, she was chosen as an ambassador for South Korea's National Police Agency in their anti-bullying campaigns in schools; she was made an honorary member of the police force in 2013 before being promoted to an honorary senior police officer in 2014 for a two-year term. In 2016, IU established a scholarship at her high school alma-mater after regularly donating there for several years.

In 2015, IU volunteered and donated to the Green Umbrella Children's Foundation. She has been a regular donor since 2018, helping to support tuition for prospective college students among low-income families, single parents, disabled children, and grandparents raising their grandchildren. She makes regular donations on her birthday, debut anniversary and special occasions to foundations helping not only children, but marginalized groups in society such as unwed mothers, elderly people, cancer patients and the homeless, both under her name and her fandom's. She has been supporting vulnerable social groups in Yangpyeong County since 2020, reaching a total of ₩145 million at the end of 2024.

In 2014, 2018 and 2023, she participated in the Ice Bucket Challenge, an Internet challenge designed to promote Amyotrophic lateral sclerosis (ALS) awareness, and donated ₩60 million. In 2019, after having to learn sign language for My Mister the year before, IU donated ₩50 million to the Deaf Senior Citizens Support Center. Her philanthropy efforts throughout the year earned her a mention in Forbes' "Asia's 2019 Heroes of Philanthropy: Catalysts For Change", being the youngest to have made the list.

During COVID-19 pandemic in 2020, she donated 3,000 pieces of medical protective clothing and about 4,600 cooling vests for nurses. In January 2023, she featured in charity song "One Step" to promote disability awareness, and in April 2023 she held a pizza party for students and teachers at Milal School, a special school for the developmentally disabled, offering rice cakes prepared by her mother.

IU has also supported natural disaster relief efforts, donating ₩100 million to help the victims of floods in August 2020, and ₩100 million for residents affected by the 2022 Uljin and Samcheok wildfires and the South Korean floods. In March 2025, she donated ₩200 million to wildfire relief efforts in North and South Gyeongsang.

As of December 2024, IU has donated ₩6 billion since her debut, and over ₩1.5 billion in 2022 alone.