Singh went to 7 Race Course Road residence of the Prime Minister to meet him.
"Very happy to meet Dr. Manmohan Singh ji & welcome him back to 7RCR. We had a great meeting," Modi tweeted later.
Earlier in the day, Singh hit out at the Modi government saying it was "harping" on corruption to divert people's attention to non-issues.
In a scathing attack, Singh alleged that institutions of democracy are under threat and the entire edifice of the welfare state is being dismantled in the guise of promoting faster economic growth.