The WSL will be an English semi-professional league, replacing the Women's Premier League as the highest level of women's football in England.
The campaign will target female fans aged nine to 15 and aim to position the players as 'sporting icons'.
Iris PR creative director Laura Weston said: 'Football is now the most popular team sport for girls in the UK. We want them to have their say so we can create match-day experiences they will enjoy.'
The agency was appointed following a pitch with three agencies. The campaign will feature PR, experiential, digital and partnership activity.