Half of young mothers regularly miss meals to provide for their children and more than a quarter have used a food bank, a study shows.
A survey of more than 300 mothers under 25 showed that money is tight, with two-thirds saying they were only just managing financially.
Barriers young mothers face in finding work can put a strain on the family budget, said the Young Women's Trust.
When asked what would help them find work, most young mums cited cheaper childcare, more jobs with flexible hours, more part-time work, as well as the attitude of employers towards pregnant women or mothers.
Young Women's Trust chief executive Carole Easton said young mothers were clearly committed to their children's upbringing, but often faced "huge challenges" in their everyday lives, including discrimination, isolation and financial difficulties.
"A shocking number are having to skip meals or turn to food banks in order to feed their children," she said.
"Young mums are telling us they want to work and become financially independent but they face huge barriers like discrimination from employers, a lack of available and affordable childcare, a lack of flexible working opportunities and inconsistent support from Jobcentre Plus. On top of that, they are entitled to less government support and lower wages because of their age."
The Trust called for access to affordable childcare, better support for young women at job centres and advertising jobs on a flexible, part-time or job share basis."
A Department for Work and Pensions spokesman said: "Encouragingly, the number of children living in working households is now at a record high but we want to go further.
"This is why we're taking steps like increasing the number of work coaches and doubling free childcare for three and four-year-olds.
"Every day our dedicated work coaches help thousands of people across the country, including young mothers, to get into work or access the support that they need."