The sitcom - created by and starring Lennon Parham and Jessica St Clair - follows two female friends who share an apartment in Brooklyn.
Only four episodes have aired on the network, with the latest instalment drawing just 2.65m viewers on April 25.
"BFF Fans: Wanted to let you know that our show is being taken off the air until the summer," Parham wrote on Twitter: "Hoping to post ep 5 & 6 online asap."
In a later message to fans, she added: "I cannot thank you enough for the love and support of our little show. You guys are truly the best."
This week, an episode of hidden-camera series Betty White's Off Their Rockers will air in the show's Wednesday 8.30 / 7.30c slot.
It is currently unclear when the final two episodes of Best Friends Forever will air on NBC.