Working fathers get paid a fifth more than men in similar jobs without children, according a new report published by the TUC.
The survey found that dads who work full-time have on average a 21% "wage bonus". Working fathers with two children earn even more (9%) compared to those with just one child.
Researchers suggest that the fatherhood wage boost may be down to dads working longer hours and putting in more effort in the office compared to their childless counterparts.
Positive discrimination could be another factor helping to push up fathers' earnings, the TUC said.
Conversely, the report found that women who become mothers before the age of 33 typically suffer a 15% wage penalty.
TUC General Secretary Frances O'Grady said: "It says much about current attitudes that men with children are seen as more committed by employers, while mothers are still often treated as liabilities."
A recent poll by the Fawcett Society found that 29% of respondents believe fathers are more committed to their jobs after having a baby, while 46% believe women are less committed after giving birth.