Akram has served as Pakistan's permanent representative to the UN previously as well, holding the office for six years between 2002 and 2008.
Lodhi has held the office of Pakistan's envoy to the UN since February 2015, the Foreign Office announced.
The sudden announcement comes a day after Imran Khan and Foreign Minister Shah Mahmood Qureshi returned to Pakistan after wrapping up their visit to the US to attend the 74th session of the UN General Assembly.
Lodhi had accompanied Imran Khan at a number of his engagements in New York during the UNGA.
The government did not provide a reason for the replacement of Lodhi. She has not been assigned any other portfolio as of now.
Following the announcement, Lodhi took to Twitter to say that she is grateful to have had the opportunity to represent the country for over four years.
"Representing Pakistan at the world's most important multilateral forum was a great privilege," she wrote, adding that she "had planned to move on after UNGA following a successful visit by the PM".
"I am humbled by the appreciation I have received for the PM's visit and the support I have also received over the years. I wish my successor Munir Akram the best of luck!" she said in a subsequent tweet.
Among other changes, Khalil Ahmad Hashmi, at present serving as Director General (UN) in the foreign ministry, has been appointed as Permanent Representative of Pakistan to the UN in Geneva.
Muhammad Aejaz has been appointed as Pakistan's ambassador to Hungary.
The Pakistani Charge d' Affaires to Pyongyang, Syed Sajjad Haider, has been posted as the new ambassador to Kuwait.
Imran Ahmad Siddiqui, presently serving as Pakistan's consul general in Toronto, Canada, has been appointed as the high commissioner of Pakistan to Bangladesh. Abdul Hamid will take over in Canada.
Pakistan's new envoy to Muscat, Oman will be Ahsan K.K. Wagan, who currently holds the office of Charge d' Affaires in Niamey, Niger.
According to the FO statement, retired Maj Gen Muhammad Saad Khattak has been appointed as the High Commissioner of Pakistan to Sri Lanka.
Abrar Hussain Hashmi has been appointed as the Pakistani consul general in Houston, Texas, USA.
( With inputs from IANS )