A Royal Navy Explosive Ordnance Disposal Team was first called to assist Sussex Police in Tarring Road on Wednesday (June 8).
Police said that officers were concerned about a 'suspicious package' that was found inside the address.
The bomb squad 'safely destroyed the package' and left the scene, police said. Click here to see video footage from the scene.
However, the Royal Navy team returned that evening to the road, which remained closed until 10.10pm.
Police said a 52-year-old man was arrested on suspicion of possession of a firearm. He was subsequently released on conditional bail whilst enquiries continued.
Residents were told to expect an 'increased police presence' while enquiries continued.
A fire engine and Scenes of Crime Officers (SOCO) were pictured on Tarring Road on Thursday.
New photographs showed a bomb disposal vehicle back in Worthing that evening, with a police van and robot.
Adur and Worthing Police announced via Twitter: “Officers are in attendance at Tarring Road in Worthing following the discovery of a suspicious substance at a property.
“The road has been closed between the junctions of Shakespeare Road and Heene Road as a precaution.
“We thank the public for their patience at this time.”
Police officers have been continuing to conduct door-to-door enquiries this morning (Friday).
In an update on Twitter just before 12.30pm, Adur and Worthing Police said Tarring Road had re-opened.They said the 'suspicious substance' was 'found to be safe', adding: "Thank you for your patience during this incident."