The whitegoods retailer generated A$2.09 billion in sales last financial year, with before-tax earnings of A$74.2 million. JB Hi-Fi's revenue was $3.95 billion last year, with EBIT of A$221.2 million.
The combined revenue would put the two chains ahead of Harvey Norman, which generated A$5.33 billion in franchisee sales in FY16 with EBIT of A$522.5 million.
The two stores will maintain their separate brands and support offices. JB Hi-Fi says the acquisition will deliver net savings of between A$15-$20 million a year, after one-off implementation costs of between A$10-$12 million in the first 12 months.
JB Hi-Fi will tap shareholders for A$394 million in equity raising to fund the deal, with the balance to be funded from around A$500 million from new and existing debt facilities.
The Good Guys chief executive Michael Ford will continue to lead the business under JB Hi-Fi's ownership. Ford had previously expressed a preference for a share market float over a sale to JB Hi-Fi.
"We are very pleased to welcome Michael and his executive team and look forward to working together to create a market-leading consumer electronics and home appliance retail group," Murray said.
Last month, the competition watchdog gave the deal the all-clear, saying it would not substantially reduce competition in either consumer electronics or whitegoods retailing, with Harvey Norman and Bing Lee among a raft of other companies in the markets.
JB Hi-Fi rejected media speculation around the deal last week.