A Child Rescue Ireland (CRI) Alert has been stood down after the child was located safe and well.
Gardaí said that the child has been located in the Dublin area.
A CRI alert had been issued after the child, 2, had been reported missing from Mayo.
Gardaí said that two people, a man and a woman aged in their 30s, have been arrested for an offence contrary to Section 15 Non-Fatal Offences Against the Person Act 1997.
They are currently detained at a Garda Station in Dublin.
Gardaí have also thanked the public for their assistance.
A CRI Alert is only issued in the most serious of cases.
Only nine alerts have been issued in the nine years the system has been operating, after launching in Ireland in 2012. This is the second one this year.