Archibald, 35, has been in caretaker charge of the Jags since Jackie McNamara departed to take over as boss of Dundee United at the end of January.
Thistle drew 2-2 at Morton in Archibald's first match in charge and they have since notched five successive wins to close within two points of Morton at the top of Division One.
Long-serving defender Archibald, who has not played for Partick since taking charge, will continue to be assisted by Scott Paterson.
Partick chairman David Beattie said: "I'm absolutely delighted to be able to confirm the appointment of Alan Archibald as Partick Thistle manager and Scott Paterson as his assistant.
"I look forward to working closely with them as we continue to work hard at providing a club that we can all take pride in."