Huawei will help Mali's Sotelma develop a wireless network by providing the equipment, setting up the network and helping Sotelma seek financing for the project, the agreement said.
Li's tour comes as Beijing tries to convert diplomatic goodwill in Africa into concrete trade and investment agreements.
David Yuang, Huawei Technologies' deputy manager in Mali, told Reuters: "The Chinese government can grant Mali concessional loans, specifying the loan is for Sotelma to develop the network. The protocol lays out the framework for co-operation."
Li, who is on a six-nation tour of Africa aimed at increasing Beijing's economic and diplomatic presence on the continent, signed a 30 million yuan ($3.72 million) donation with his Malian counterpart Moctar Ouane as part of an accord for economic and technological co-operation.
Africa's third-largest gold producer after South Africa and Ghana, Mali is one of the world's poorest nations, with more than 90% of the population living on less than $2 a day.
After visiting Cape Verde and Senegal, which resumed diplomatic ties with China in October, the Chinese foreign minister will now head to Liberia and major oil producers Nigeria and Libya.
Mali is also desperate to become an oil producer and has given exploration rights to several companies, including Chinese state-run oil and gas firm Sinopec Corp.
Ouane said greater agricultural co-operation and cotton sales were also discussed. Mali is one of sub-Saharan Africa's top cotton producers. Chinese entrepreneurs are already involved in the sugar, health and textile industries.
China has steadily built up its influence in the world's poorest continent since the 1960s and 1970s when it offered its support to newly independent African states and threw its weight behind independence movements.
Li will attend Johnson-Sirleaf's
Beijing says it offers economic aid and co-operation "without strings", in contrast to Western countries which often demand commitments from poor African countries to fight corruption and improve human rights.
Critics say the Chinese approach undermines international efforts to introduce good governance reforms in Africa.
In Liberia, Li will attend the inauguration ceremony for Ellen Johnson-Sirleaf, who will be sworn in as Africa's first elected female president on 16 January.