Sports Direct employs at least 3,500 agency workers at its site in Shirebrook, Derbyshire.
While filming in the town, the BBC was shown houses "carved into flats", including one with rooms partitioned down the middle of its windows.
Bolsover Council admitted it was caught off guard by the influx of workers.
Figures obtained by the BBC also show 46 housing complaints relating to overcrowding, repairs and conditions were made from April 2015 to 21 December last year - up from 16 in 2005-06.
The Sports Direct agency workers, largely employed in the company's warehouse, come mainly countries such as  Poland, Romania, Bulgaria, Latvia, Lithuania and Albania.
There are 500 permanent staff at the site.
The council estimates 1,500 people have moved to Shirebrook - which has a population of more than 13,000 - in the last four years, with many renting rooms in houses near the company's headquarters.
Police community support officer (PCSO) Steve Cathcart said: "There's been an influx of Eastern Europeans and the landlords that own the houses are carving these houses up into flats.
"Our concern is the fire risk, the safety to these people that are moving in."
Police said more than 30 properties in the area were a particular worry.
The police said one of the occupants in the house where two rooms had been visibly partitioned up to the windows works at Sports Direct, but added the resident had "no fire doors".
Bolsover councillor Karl Reid, who is responsible for community cohesion, admitted the authority had not adequately prepared itself for the sudden increase in Shirebrook's population.
"[On the window dividers] that is not acceptable and that will be investigated," he said.
"It was a gradual thing, then suddenly there was a massive spurt. I think that's where we may have got it wrong or we weren't on the ball for it, and I have to accept that."
The authority said it had introduced public spaces protection orders to stop people drinking and urinating on the town's streets.
It said it was also closing off a footpath near Sports Direct because of anti-social behaviour, including human defecation.
Since November, it said 20 fines have been handed out - 19 for drinking and one for urinating - to people in breach of these orders.
Mr Reid added Sports Direct's senior staff was working with them for the first time in more than a decade.
The company - which has declined to comment - are part of a multi-agency group called Shirebrook Forward.
"They've changed their tack," Mr Reid said.
"They've now - over the last six months - come to us and engaged with us on a senior management level."
Sports Direct said in December they will be reviewing all agency workers' terms and conditions.
It follows a BBC Inside Out investigation last October into the company's warehouse working practices.
The review will be overseen by majority shareholder Mike Ashley - who also owns Newcastle United Football Club.
Inside Out is broadcast on BBC One East Midlands at 19:30 on Monday 22 February and nationwide for 30 days thereafter on the iPlayer.
Police say they have safety concerns about overcrowded houses in the town where one of Europe's largest sports retailers is based.