The 35-year-old, who made his top-flight debut for the Bianconeri in 2004, notched his 159th league goal for the north-east club after Alessandro Diamanti had put Bologna on track for their first win of the new season.
The point keeps European hopefuls Udinese in a healthy position in the fledgling league table while Stefano Pioli's Bologna are floundering in the bottom half with only two points on the board.
Di Natale checked Bologna were awake with a snapshot in the fifth minute but Cesare Natali was concentrating and made the block.
The Udinese veteran tried his luck from outside the area next, his shot sailing over the bar, before Davide Moscardelli directed a weak shot at Ivan Kelava in the home goal.
Gianluca Curci was the first goalkeeper to survive a real test, though, when Luis Muriel twisted and turned to get a powerful shot away at the near post.
Roberto Pereyra perhaps went closest to breaking the deadlock in a lacklustre first half but his header from an Andrea Lazzari cross was just off-target.
Kevala found himself dealing with a header when play resumed as Rolando Bianchi got onto a high ball from Diamanti.
Udinese steadily conceded ground with a series of needless fouls as the hour mark approached, and they were duly punished in the 71st minute.
After Emmanuel Agyemang-Badu was caught grappling with Michele Pazienza on the edge of the D, former West Ham striker Diamanti stepped up to drive a wonderful free-kick into the Udinese goal.
Di Natale was clearly unimpressed with the visitors' attempts to steal his thunder and responded appropriately on his milestone appearance in black and white.
There were five minutes remaining in Udine when the evergreen 35-year-old volleyed Muriel's chipped pass beyond Curci to rescue a point with his first Serie A goal of the season.