According to Turkish presidential sources, Putin phoned Erdogan and also discussed more cooperation on a cease-fire in Syria.
Slovenian President Borut Pahor, Macedonian President Gjorge Ivanov, Albanian Prime Minister Edi Rama and Lebanese Prime Minister Saad al-Hariri also congratulated Erdogan over the phone.
On Sunday, a majority of Turkish voters cast ballots in favor of 18 constitutional amendments that will, among other things, see Turkey switch from a parliamentary to a presidential system of governance.
According to unofficial results, the Yes campaign won with 51.41 percent, while the No votes stood at 48.59 percent. Voter turnout was 85.46 percent.