A woman aged 19 and a 24-year-old man were the property at the time. The man was taken to Harrogate District Hospital and received treatment for the effects of smoke inhalation. The woman did not require any medical assistance.
The fire caused extensive smoke damage to all rooms and fire damage to one of the ground floor rooms.
Two men aged 33 and 26, both from Harrogate, have been arrested in connection with the incident and remain in police custody.
Detective Sergeant Alan Browne, of Harrogate CID, said: Thankfully neither of the occupants of the flat were seriously injured as a result of this fire. However, the consequences could have been far worse.
If you have any information which could help my investigation I urge you to come forward and contact the police straight away.
Anyone who can assist with this enquiry should contact Harrogate CID on 101, select option 2 and ask for Alan Browne. Alternatively, information can be emailed to Alan.firstname.lastname@example.org
Or call Crimestoppers anonymously on 0800 555111, quoting reference number 12140144035.