Police found the woman’s body shortly after 7pm on Boxing Day in Severn Road, Blackpool. Emergency services were dispatched to the property after reports that a woman had become unresponsive.
A man from Manchester has been arrested on suspicion of murder and remains in custody.
Lancashire Constabulary has issued an appeal for witnesses who may have seen someone entering or exiting from number 32 Severn Street between 12pm on Christmas Day and 6.30pm on Boxing Day.
Police are also asking anyone with a dash cam or CCTV footage to come forward.
Det Supt Neil Drummond said: “First of all my thoughts are with the loved ones of the deceased at this difficult time.
“We have launched a homicide investigation to establish the full circumstances of her death.
“While we have made an arrest, our investigation is still ongoing and you will see officers in the area investigating today.
“If you have any information that you think may help our investigation, please contact agents on the scene.”