
The planes were only cleared to return to the skies in late 2020, and Boeing has also suffered from the collapse of the travel industry due to the Covid-19 pandemic.
Southwest’s order is worth US$12.5 billion at catalogue prices.
The airline also took options to buy 155 more MAX planes.
The deal raises Southwest’s order book for 737-7 and its bigger 737-8 model to 380, according to Boeing.
More than 30 have already been delivered.
Boeing was hit with 655 cancelations or plane order conversions last year, and in February, Boeing again saw more cancelations than new orders.
Earlier this month, investment firm 777 Partners ordered 24 of Boeing’s 737 MAX aircraft, with an option to order 60 more.