In 2005, Němcová published her autobiography Love Always, Petra ( ISBN 0446579130).
Her autobiography, Love Always, Petra, was released in 2005 from which 100% of the proceeds were donated towards helping children affected both by the 2004 tsunami in Thailand and ongoing natural disasters worldwide.
In 2005, Němcová founded the Happy Hearts Fund (HHF), a charitable organization and campaign formed after the tsunami of 2004. The main mission of Happy Hearts Fund has been to rebuild and renew schools affected by natural disasters. As a result of programmes run by the Happy Hearts Fund, 176 schools have been rebuilt world-wide in 10 countries including Thailand, Indonesia, Haiti, Nepal, Peru, Mexico and The Philippines. Němcová has been heavily involved on an every day basis since establishing the Happy Hearts Fund, helping to establish long term strategies, as well as outlining the vision which has led to the organisations long term success. Her personal experience during the 2004 Boxing Day Tsunami gave her a deep understanding of the power of Mother Nature, allowing her to connect with those in need, bolstering the success of her work through the organisation. In late 2017, the Happy Hearts Fund merged with fellow non-profit organisation All Hands Volunteers to create All Hands And Hearts - Smart Response. As a result, Němcová now acts as co-founder and vice chair of All Hands And Hearts alongside All Hands Volunteers founder David Campbell.
Glamour magazine awarded Němcová a "Survivor Award" in 2005 for her charity work following her tsunami ordeal.