The 24-year-old man was arrested on Wednesday after officers raided properties at South Melbourne, along with Tarneit, Truganina and Albion in Melbourne's west.
He will be charged with offences including intentionally causing serious injury and illegally possessing a firearm, Victoria Police said.
A 23-year-old man from Werribee in Melbourne's southwest was also arrested but released pending further inquiries.
Police arrested the 24-year-old almost three weeks after a gunman wearing a white hazmat suit opened fire on a 76-year-old man who answered a knock at his front door on Canterbury Rd in Middle Park about 7.50pm on August 17.
He was shot in the leg and hospitalised but survived the attack, which was described as "brazen" by police.
Two women inside the home, aged 72 and 39, were uninjured.
The gunman ran away and was seen heading towards Albert Park Lake, with officers later appealing for members of the public to help their manhunt.
Police, in announcing the arrest on Monday, said they seized a white Hyundai as part of their investigation.
The 24-year-old man, from Tarneit, was due to front Melbourne Magistrates Court on Wednesday afternoon.
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