Rutherford, who holds the Olympic, world, Commonwealth and European titles, won gold at London 2012 in what British media later dubbed Super Saturday when three British athletes topped the podium in the space of an hour.
He looked in danger of an early exit in Rio, however, making two foul jumps before recording a distance of 7.90 metres on his last attempt.
"I know 7.90 metres is not good but it was just a matter of making (the) finals," Rutherford said.
"Going into the final round I definitely wasn't as stressed as my family were at home," he added. "For me it's one of these where you draw on all the experiences that you've had.
The 29-year-old will now defend his title against challengers including China's Jianan Wang and Jeff Henderson of the United States, who qualified in first and second place with jumps measuring 8.24m and 8.20m.
Another likely contender is Team USA's Jarrion Lawson, who jumped 8.58 metres at the U.S. Olympic trials and in June was the first man to win the 100 metres, 200 metres and long jump since 1930s track-and-field star Jesse Owens at the U.S. collegiate championships.
Rutherford said his close brush with an early exit from the Rio Games was the nature of the competition.
"These are stressful events at times for that exact ... scenario," he said. "You saw big names go out of the qualification yet again – I was very nearly close to being one of them."
(This story corrects month in para 7.)
(Reporting by Jack Stubbs; Editing by Ed Osmond)
