Rudd included 11 women in his ministry, potentially helping him counter a backlash from female voters after he defeated Gillard, Australia's first female prime minister, in a party leadership vote on Wednesday.
Labor reinstalled Rudd, who was prime minister from late 2007 until mid-2010, after dire opinion polls indicated the government would suffer an overwhelming defeat under Gillard.
An influential Newspoll in The Australian newspaper on Monday found Rudd's return had given the Labor Party a significant boost, lifting the party's vote by six percentage points from 43 percent to 49 percent over the past week.
The poll showed the conservative opposition was still ahead on the key two-party vote after the distribution of preferences from minor parties, although its support fell from 57 percent to 51 over the past week.
Rudd has also overtaken opposition leader Tony Abbott as preferred prime minister, with 49 percent support compared with 35 percent for Abbott. Gillard had consistently trailed Abbott as preferred prime minister.
"Rudd's resurrection has changed the political dynamic and shifted the pressure to Abbott," wrote The Australian's political editor Dennis Shanahan.
Rudd can call an election for any time from mid-August, but is considering delaying the vote until October to give his government time to review key policies. The government could lose power if it drops just one seat in the 150-seat parliament.
Rudd rewarded supporters in his new ministry, with former defense minister Joel Fitzgibbon returning to Cabinet as agriculture minister and former industry minister Kim Carr back as minister for innovation and higher education.
Last week, Rudd appointed his key supporter Chris Bowen as treasurer to replace Gillard loyalist Wayne Swan. Finance Minister Penny Wong, who backed Rudd in the leadership vote, retained her portfolio.
Rudd rejected suggestions the appointments were political and said all of his ministers were chosen on merit.
(Reporting by James Grubel; Editing by Paul Tait)