No one was hurt but Port Khalid was closed for most of the day while emergency crews battled overnight to put out the blaze that broke out around 10:30pm on Friday.
Rashed al-Leem, director-general of Sharjah's Hamiriyah Ports, Customs and Duty Free Zone, said that the port had not been badly damaged.
'Activity at the port did not stop except for a short period of no more than seven hours ... to facilitate the security forces bringing in the necessary fire-extinguishing equipment,' Mr Leem told the state news agency WAM. 'After that activity returned to what it was before.'
Sharjah is one of seven emirates that comprise the United Arab Emirates (UAE), which include the Gulf trade and tourism hub of Dubai. A busy trade and population centre, Sharjah is one of the larger and more prominent members of the UAE.
Port Khalid, on Sharjah's Gulf coast, handles the majority of its general cargo traffic and has a 13-berth deep-water harbour. Sharjah's other main port is at Khor Fakkan on the Indian Ocean coast, well away from the blaze.
UAE Interior Minister Saif bin Zayed al-Nahayan, who visited the site, thanked the emergency services for getting the fire under control before it spread to other areas of the port and said authorities were looking into the incident to prevent it from happening again. An eyewitness said the flames had reached a height of 200 metres.