The 26-year-old was held on Wednesday and is currently being questioned by detectives about information provided to the investigation. It is the first arrest in the case.
Mr McKeague, 23, whose girlfriend, April Oliver, 21, is expecting their first baby, disappeared after going out with friends on September 24.
Officers have issued CCTV footage of two people who were seen on foot in Brentgovel Street or the “horseshoe” area of the town, around the time of the last sighting of him.
Det Supt Katie Elliott said: “We are continuing to make progress on the investigation and we will be starting the landfill site search as soon as the preparatory work is complete.
“We have been carrying out a lot of inquiries behind the scenes and our work continues to find the truth about what happened to Corrie.”
At around 03:25, he walked into the “horseshoe” loading bay area.
It has been proven an individual cannot leave the area on foot without being seen on CCTV, but Mr Mckeague was not caught on camera again.
RAF Honington reported Mr Mckeague’s disappearance to police on 26 September when he did not turn up to parade at 11:30.
Mr Mckeague’s mother, Nicola Urquhart, has previously said she has no faith police would find him and launched a crowdfunding campaign to hire a private investigator.
Officers have confirmed the man arrested is not the driver of a bin lorry that collected waste from the area where Corrie was last seen.
Suffolk Police said in a statement: “He has been taken into custody where he will be interviewed on suspicion of attempting to pervert the course of justice relating to information provided to the investigation.”