The agreements were signed in the presence of His Highness the Emir Sheikh Tamim bin Hamad al-Thani and Bulgarian Prime Minister Boyko Borissov.
The agreements cover co-operation in youth and sports, energy and a memorandum of understanding between Qatar University and Sofia University.
Members of the delegation accompanying the Emir and Bulgarian ministers and senior officials attended the signing ceremony.
Earlier the Emir and Borissov held bilateral talks.
At the outset of the session, the Bulgaria's prime minister welcomed the Emir, pointing that the two countries enjoy close relations, boosted by the continuous communication between officials and joint projects between the two countries.
He also said he looked forward to agreements on new projects in the near future.
The Emir expressed thanks for the hospitality. He also congratulated the Bulgarian government and people on the occasion of the Bulgarian National Day.
The Emir said the two countries have great ambitions and they are determined to make every effort to support and develop bilateral relations in various fields, especially investment.
His Highness the Emir Sheikh Tamim bin Hamad al-Thani chairing a session of official talks with the Bulgarian President Rumen Radev in Sofia.
He said the relations between the two countries are strong and historical, pointing to visits between senior officials of the two countries, and stressing at the same time that his visit will contribute to pushing relations further.
During the talks, the two sides discussed means of enhancing the friendly relations and co-operation for the benefit of their peoples.
The talks also dealt with several regional and international issues.
The Emir extended an invitation to the Bulgarian prime minister to visit Qatar, which he welcomed.
He also congratulated the prime minister of Bulgaria on assuming the presidency of the European Union’s current session.
The Emir also held talks with Bulgarian President Rumen Radev and discussed bilateral relations and prospects for developing them at various levels, especially political, cultural,
economic and investment.
They also reviewed a number of regional and international issues.
Later the two leaders undertook a tour of Sofia.
They visited Bulgaria's National History Museum, where the Emir was briefed on the most important milestones in the history of Sofia, Bulgaria and the Balkans in general, and viewed antique art works, old coins, maps and paintings exhibited in the museum.
They also visited the headquarters of the Bulgarian Football Federation where they were briefed about the federation and had a general conversation on sports and football.
Earlier, the Emir attended a luncheon banquet hosted by Radev at the Presidential Palace.
On his arrival at the palace, the Emir was accorded an official reception.
Radev led well-wishers to welcome the Emir.
The reception ceremony began with the Qatari and Bulgarian national anthems.
The Emir then inspected a Guard of Honour.
Later in the evening, the Emir left Sofia after a two-day state visit.
He sent cables to the president and prime minister of Bulgaria, expressing thanks for the hospitality.