Sony has begun restoring the PlayStation Network games service nearly a month after the massive security breach.
Gamers and security experts have criticised Sony for its handling of the incident, which cast a shadow over its plans to combine the strengths of its content and hardware products via online services.
Sony has apologised to customers for the closure of the online gaming service, and said a range of new security measures had been introduced.
These included an early warning system that could alert the company to any attempt to penetrate the network.
"I can't thank you enough for your patience and support during this time," Sony No. 2 Kazuo Hirai said.
"We are taking aggressive action at all levels to address the concerns that were raised by this incident, and are making consumer data protection a full-time, company wide commitment."
However some users have switched to rival Microsoft's Xbox Live games service during the extended outage.
In what is thought to be the biggest security breach of its kind, hackers accessed personal information from 77 million PlayStation Network accounts, which may have included credit card information.
Sony shut down the PlayStation Network last month after detecting unusual activity, but did not alert users to the extent of the security leak until a week later.
The Qriocity online music and movie service was also closed.
The company later found out that a separate online games service had also been penetrated, allowing access to another 25 million user accounts.
Sony said the restoration of PlayStation Network and Qriocity online movie and music services would take place on a country by country basis and that it expected the process to be complete by May 31.
Sony Online Entertainment services are also being restored and customers will be offered free game time as compensation for the outage, the company said.
Sony also said it had appointed an acting chief information officer to oversee security on its networks.