In 2005, the 15th anniversary since the official establishment of diplomatic relations between Bulgaria and the Vatican and the 80th anniversary since the assignment to Bulgaria of Monsignor Roncally are marked. Yet the relations between the Holy See and the Bulgarian state have a history of long standing. The beginning dates back to the mid-19th c. In the wake of foiled negotiations with Byzantium on recognition of the Bulgarian autocephalous church, King Boris I approached Rome. In the summer of 866 Pope Nicholas I received in Rome envoys of the Bulgarian king, the boyars Peter, Martin and Ivan. The envoys came back in the fall and brought to the Bulgarian capital city the Pope's answers to the 106 questions of King Boris I concerning the foundations of the Christian faith and the assent on principle to establish a Bulgarian autocephalous church. Along with the envoys, two bishops, Formoza and Paul arrived from Rome to Bulgaria.

Very close were the relations of Bulgaria with Rome in the days of the Bulgarian King Kaloyan. As a result, in end-1199, Pope Innocent III dispatched special envoys to Tarnovo, the capital of the Second Bulgarian Kingdom. The envoys delivered a letter to Bulgaria's King broaching issues of the recognition of the Bulgarian state. In 1202 King Kaloyan started negotiations with the Pope to wrap them up successfully two years later. The Bulgarian potentate was conferred the title of a king and mintage right. Bulgarian Bishop Basil was conferred Primate title. In November 1204, Kaloyan was ceremonially crowned king. The union with Rome is deemed to be a great diplomatic breakthrough.

Other Bulgarian potentates also maintained good relations with the head of the Latin Church. The same applies to the period after the liberation of Bulgaria from the Ottoman yoke. Pope Leo XIII held Bulgaria dear and had a specific vision of the country's position and role in South-Eastern Europe. He underscored the mission of the Holy Brothers Cyril and Methodius and for the first time ever included them on the calendar of the ecumenical church, which is a deep appreciation of Bulgarian culture and letters.

The relations between the Vatican and Bulgaria were extended even further in 1925, when Monsignor Angelo Roncally, later Pope John XXIII, also known across Italy as “The Bulgarian Pope”, arrived in Sofia in his capacity of Apostolic Legate. His residence in Sofia was in 11 Avgust Street. The term of his successor Giuseppe Mazzoni lasted until 1945. After Francesco Galloni, interim head of the office of the Apostolic Legate left the country in 1949, the relations between Bulgaria and the Vatican were severed for quite a while.

Yet the contacts and cultural exchange were retained. Bulgarian delegations visited the Vatican on an annual basis on the occasion of May 24th, the Day of Bulgarian Education and Culture and of Slav Letters, of the Holy Brothers Cyril and Methodius, with the participation of top Latin clergy. Bulgarian researchers were granted access to the secret archives of the Vatican as well as to the Apostolic Library to find a number of documents and manuscripts containing records on Bulgarian history.

In 1975, Todor Zhivkov, president of the State Council went on a visit to the Vatican and held a meeting with Pope Paul VI – the first ever meeting of Bulgaria's head of state with the head of the Latin Church in this country's history. Five years later, on December 31, 1980 Pope John Paul II proclaimed Holy Brothers Cyril and Methodius Co-patrons of Europe along with St. Benedict.

On November 5, 1990 visiting Bulgarian Minister of Foreign Affairs Lyuben Gotsev was received in private audience by Pope John Paul II. During the talks, the bilateral relations were revised and a will for their further development was voiced. Ideas were shared also of extending contacts in the domains of culture and religion. At the reception given on the occasion the issue was broached of establishing diplomatic relations with the Holy See. Cardinal Agostino Casaroli, Secretary Emeritus of State received Minister Gotsev in line with the issue.

As a result from the talks held and the will expressed by both parties to extend the relations, official diplomatic relations between Bulgaria and the Vatican were established at ambassadorial level on December 6, 1990. “The Republic of Bulgaria and the Holy See,” reads the inked agreement, “led by their will to establish friendly relationships between the two countries, decided by common consent to establish diplomatic relations.”

In June 1991, the Apostolic Nunciature opened doors in Sofia with Msgr. Mario Rizzi, Apostolic Nuncio Emeritus as the representative of the Holy See to Bulgaria. He presented his credentials on July 9 of the same year. Mr. Kiril Marichkov was appointed ambassador of the Republic of Bulgaria to the Vatican presenting his credentials to Pope John Paul II on October 11, 1991.

In the summer of the same year, by decision of the Council of Ministers of the Republic of Bulgaria Catholic priests, sentenced on concocted charges in 1952, were fully exonerated. On February 15, 1998 at a sermon at the St. Peter Basilica in Rome attended by the Bulgarian delegation, Pope John Paul II beatified Bishop Evgeni Bosilkov from Ruse on the Danube, who was executed in 1952.

Bulgarian delegation attended also the Jubilee Year 2000 celebrations, occasioned by the 2000th Anniversary of the Birth of Christ. In the framework of the OSCE 9th Ministerial Council, held on 3-4 December 2001, the then Bulgaria's Foreign Minister Solomon Passy held talks with Monsignor Jean-Louis Tauran, Vatican Secretary for Relations with the States. In the period 2000–02, three Bulgarian ministers were received in audience by the Pontiff and met with Vatican Secretary of State, Cardinal Angelo Sodano on the occasion of May 24, the Day of Slav Letters: Nadezhda Mihaylova (Minister of Foreign Affairs), Prof. Dimiter Dimitrov (Minister of Education and Science) and Solomon Passy (Minister of Foreign Affairs). The landmark event in the relations between the Holy See and Bulgaria in the modern era was the historic visit made by Pope John Paul II on May 23–26, 2002. His Holiness was welcome here with great honour, he had meetings with the president, the prime minister, with the head of the Bulgarian Orthodox Church and representatives of other denominations, with intellectuals and citizens. His Holiness visited the Rila Monastery and officiated at a solemn mass in the southern city of Plovdiv, beatifying three Bulgarian Catholic priests, who also died the death of martyrs: Kamen Vichev, Josaphat Shishkov and Pavel Djidjov. In 2003, a delegation of the Bulgarian Orthodox Church paid a visit to the Vatican. In end-May of the same year Prime Minister Simeon Saxe-Coburg-Gotha was also received in audience by Pope John Paul II. Prof. Ognyan Gerdjikov, President of the National Assembly headed a delegation to Rome for the celebrations of May 24th. He was received in audience by the Pontiff and asked His Holiness for help on the HIV-trial against the six Bulgarian nurses in Libya.

In October of the same year, talks were held in the Vatican on Bulgaria holding OSCE chairmanship, between Bulgaria's Deputy Foreign Minister Gergana Grancharova and Monsignor Pietro Parolin, undersecretary of the Section for Relations with States of the Vatican Secretariat of State; the latter was extended an invitation to visit Bulgaria.

Among the delegations for the funeral of the Roman Pontiff was a Bulgarian delegation headed by President Georgi Parvanov with European Affairs Minister Meglena Kuneva, Neofit, Metropolitan of Dorostol and Cherven, and Dometiyan, Metropolitan of Vidin on the delegation.

On the occasion of the election of a new Roman Pontiff, Pope Benedict XVI on April 19, 2005 President Georgi Parvanov, Premier Simeon Saxe-Coburg-Gotha and Foreign Minister Solomon Passy sent telegrams of congratulations.

“I believe,” reads the congratulation of President Parvanov, “that led by you the Holy See as a universally respected institution along with the representatives of the rest of the denominations would retain its very important position both in solving these problems and in the unity of peoples in their struggle for peace, prosperity and justice in the future development of our civilization.”

On May 23, 2005, on the occasion of the celebration of the Holy Brothers Cyril and Methodius, Pope Benedict XVI received President Georgi Parvanov in audience. At the meeting, Bulgaria's president extended an invitation to His Holiness to visit this country at His Holiness' convenience. A request was made part of the relics of St. Cyril to be brought to Bulgaria for a Center of Saints Cyril and Methodius to be established with the assistance of the Holy See. Pope Benedict XVI responded with heartfelt words to the Bulgarian people: “Bulgaria is aware that it is the country's duty before the other peoples to bridge the East and the West. Addressing you, I'd like to encourage your people to accomplish this specific social and political mission.”

During the talks, the Holy Father stated his readiness for continuing and extending the dialogue between the Vatican and Bulgaria and for support for Bulgaria's aspiration for full-fledged EU membership. Emerging from the audience, President Georgi Parvanov met and held talks with Cardinal Angelo Sodano, Secretary of State in the vein of the traditional contacts, opening further opportunities for the development of the good bilateral relations.