Santosh Alkar, a diabetic and unemployed, was found hanging at his residence in suburban Chakala by his sister this afternoon, police said.
His son Sunil (10) and daughter Mitali (7) were found strangulated, they said.
Alkar has left a suicide note in which he said he was frustrated with the ailment and unable to fulfil the wishes of his children and wife Radha, who is working as a housemaid with a city-based family staying in Singapore, police said.
Radha had been taken to Singapore by the family.
"Radha has been working there for quite sometime and used to send money to her husband and children regularly," Pradeep Gosavi, Senior Inspector at Andheri Police Station, said.
Alkar was taking caring of his kids who were studying here.
In the suicide note, Alkar has appreciated his wife for working hard to meet the family requirements and apologised for not fulfilling her wishes. Alkar wrote he killed his children because there would be nobody to take care of them after his death, police said.