The emir named Prime Minister Abdullah bin Nasser bin Khalifa Al Thani to lead the Qatari delegation to the summit of the 40th Persian Gulf Cooperation Council ((P)GCC) summit, the official Qatar News Agency reported.
Sheikh Abdullah will be the most senior Qatari official to attend the gathering of Persian Gulf leaders since the emir attended a 2017 summit held in Kuwait, at which Riyadh and its allies sent more junior officials.
Saudi Arabia, the United Arab Emirates (UAE), Bahrain, and non-PGCC Egypt cut diplomatic and economic ties with Qatar in June 2017 over allegations of supporting terrorism. Doha denies the accusations and says the boycott aims to impinge on its sovereignty.
Last week, Qatar's foreign minister told a conference in Rome that the crisis has "moved from stalemate to progress". He also admitted that talks had taken place between Doha and Riyadh but did not provide further details.
Some observers said the summit could pave the way for a "reconciliation conference".
Others remain sceptical, saying Saudi King Salman bin Abdulaziz's written invitation to Sheikh Tamim was only following protocol.
Qatar's prime minister attended a series of talks in Saudi Arabia in May, one of the first high-level contacts of the two-year boycott.