Greece (which had gained its independence in 1832) and Italy established diplomatic relations in 1861, immediately upon Italy's unification.
Italian philhellenes had contributed to the Greek independence, such as the jurist Vincenzo Gallina, Annibale Santorre di Rossi de Pomarolo, Count of Santarosa and Giuseppe Rosaroll.

Throughout the 19th century, Italian philhellenes continued to support Greece politically and militarily.
For example, Ricciotti Garibaldi led a volunteer expedition (Garibaldini) in the Greco-Turkish War of 1897.
A group of Garibaldini, headed by the Greek poet Lorentzos Mavilis, fought also with the Greek side during the Balkan Wars.

In early 1912, during the Italo-Turkish War, Italy occupied the predominantly Greek-inhabited Dodecanese Islands in the Aegean Sea from the Ottoman Empire.
Although later with the 1919 Venizelos–Tittoni agreement, Italy promised to cede them to Greece, Carlo Sforza in 1920 renounced the accord.

In 1913, after the end of the First Balkan War, lands of Northern Epirus were ceded to Greece, but Italy challenged the decision and in the Treaty of London the region was given to the newly created Albania.
The local Greek population was enraged and created the Autonomous Republic of Northern Epirus, before it was reluctantly ceded to Albania, with peace assured by Italian peacekeeping force until 1919.
Italy rejected the decision because it didn't want Greece to control both sides of the Straits of Corfu.
In addition, although Sazan Island was ceded to Greece in 1864 as part of the Diapontia Islands, Greece ceded the island to the newly independent Albania in 1914 after the pressure of Italy, and since Greece didn't want to risk a war with Italy.
Italy took possession of the island in 1920 and kept it through World War II.

During the World War I, both Italy and Greece were members of the Allies and fought against the Central Powers but when the Italians found that Greece had been promised land in Anatolia at the Paris Peace Conference, 1919, the Italian delegation withdrew from the conference for several months.
Italy occupied parts of Anatolia which threatened the Greek occupation zone and the city of Smyrna.
Greek troops were landed and the Greco-Turkish War (1919–22) began with Greek troops advanced into Anatolia.
Turkish forces eventually defeated the Greeks and with Italian aid, recovered the lost territory, including Smyrna.

When the Italian Fascists gained power in 1922, they persecuted the Greek-speakers in Italy.

In 1923, the new Italian Prime Minister Benito Mussolini used the murder of an Italian general on the Greco-Albanian border as a pretext to bombard and temporarily occupy Corfu, due to Corfu's strategic position at the entrance of the Adriatic Sea.

The Greek general Theodoros Pangalos, who governed Greece as a dictator in 1925–26, sought to revise the Treaty of Lausanne of 1923 and launch a revanchist war against Turkey.
To this end, Pangalos sought Italian diplomatic support, as Italy still had ambitions in Anatolia, but in the event, nothing came of his overtures to Mussolini.
After the fall of Pangalos and the restoration of relative political stability in 1926, efforts were undertaken to normalize relations with Greece's neighbours.
To this end, the Greek government, especially Foreign Minister Andreas Michalakopoulos, put renewed emphasis on improving relations with Italy, leading to the signature of a trade agreement in November 1926.
The Italian–Greek rapprochement had a positive impact on Greek relations with other Balkan countries, and after 1928 was continued by the new government of Eleftherios Venizelos, culminating in the treaty of friendship signed by Venizelos in Rome on 23 September 1928.
Mussolini favoured this treaty, as it aided in his efforts to diplomatically isolate Yugoslavia from potential Balkan allies.
An offer of alliance between the two countries was rebuffed by Venizelos but during the talks Mussolini personally offered "to guarantee Greek sovereignty" on Macedonia and assured Venizelos that in case of an external attack on Thessa
Greece (which had gained its independence in 1832) and Italy established diplomatic relations in 1861, immediately upon Italy's unification. Italian philhellenes had contributed to the Greek independence, such as the jurist Vincenzo Gallina, Annibale Santorre di Rossi de Pomarolo, Count of Santarosa and Giuseppe Rosaroll.
Throughout the 19th century, Italian philhellenes continued to support Greece politically and militarily. For example, Ricciotti Garibaldi led a volunteer expedition (Garibaldini) in the Greco-Turkish War of 1897. A group of Garibaldini, headed by the Greek poet Lorentzos Mavilis, fought also with the Greek side during the Balkan Wars.
In early 1912, during the Italo-Turkish War, Italy occupied the predominantly Greek-inhabited Dodecanese Islands in the Aegean Sea from the Ottoman Empire. Although later with the 1919 Venizelos–Tittoni agreement, Italy promised to cede them to Greece, Carlo Sforza in 1920 renounced the accord. 
In 1913, after the end of the First Balkan War, lands of Northern Epirus were ceded to Greece, but Italy challenged the decision and in the Treaty of London the region was given to the newly created Albania. The local Greek population was enraged and created the Autonomous Republic of Northern Epirus, before it was reluctantly ceded to Albania, with peace assured by Italian peacekeeping force until 1919. Italy rejected the decision because it didn't want Greece to control both sides of the Straits of Corfu. In addition, although Sazan Island was ceded to Greece in 1864 as part of the Diapontia Islands, Greece ceded the island to the newly independent Albania in 1914 after the pressure of Italy, and since Greece didn't want to risk a war with Italy. Italy took possession of the island in 1920 and kept it through World War II. 
During the World War I, both Italy and Greece were members of the Allies and fought against the Central Powers but when the Italians found that Greece had been promised land in Anatolia at the Paris Peace Conference, 1919, the Italian delegation withdrew from the conference for several months. Italy occupied parts of Anatolia which threatened the Greek occupation zone and the city of Smyrna. Greek troops were landed and the Greco-Turkish War (1919–22) began with Greek troops advanced into Anatolia. Turkish forces eventually defeated the Greeks and with Italian aid, recovered the lost territory, including Smyrna. 
When the Italian Fascists gained power in 1922, they persecuted the Greek-speakers in Italy.
In 1923, the new Italian Prime Minister Benito Mussolini used the murder of an Italian general on the Greco-Albanian border as a pretext to bombard and temporarily occupy Corfu, due to Corfu's strategic position at the entrance of the Adriatic Sea.
The Greek general Theodoros Pangalos, who governed Greece as a dictator in 1925–26, sought to revise the Treaty of Lausanne of 1923 and launch a revanchist war against Turkey. To this end, Pangalos sought Italian diplomatic support, as Italy still had ambitions in Anatolia, but in the event, nothing came of his overtures to Mussolini. After the fall of Pangalos and the restoration of relative political stability in 1926, efforts were undertaken to normalize relations with Greece's neighbours. To this end, the Greek government, especially Foreign Minister Andreas Michalakopoulos, put renewed emphasis on improving relations with Italy, leading to the signature of a trade agreement in November 1926. The Italian–Greek rapprochement had a positive impact on Greek relations with other Balkan countries, and after 1928 was continued by the new government of Eleftherios Venizelos, culminating in the treaty of friendship signed by Venizelos in Rome on 23 September 1928. Mussolini favoured this treaty, as it aided in his efforts to diplomatically isolate Yugoslavia from potential Balkan allies. An offer of alliance between the two countries was rebuffed by Venizelos but during the talks Mussolini personally offered "to guarantee Greek sovereignty" on Macedonia and assured Venizelos that in case of an external attack on Thessa
Greece–Italy relations