Stefano Pioli's side were on course for a sixth consecutive league triumph after Senad Lulic's first-half strike put them in front.
But Verona, who had seen a Toni effort disallowed for offside before Vangelis Moras' defensive error handed Lazio the initiative, hit back when Luis Cavanda conceded a spot-kick - earning a second yellow card in the process.
Toni kept his cool to convert the leveller and secure only his second top-flight goal of the campaign, but the home side came up short in their search for a winner.
They did, however, end a three-game losing streak in an impressive display at the Stadio Marc'Antonio Bentegodi on Thursday.
Toni was thwarted by an offside flag after emphatically drilling home from inside the box in the 21st minute and his frustration was compounded when Verona fell behind.
Lulic took advantage of Moras' poor attempt at a clearance to prod home from close range just three minutes before the interval.
The hosts were forced into a double change at the break as injured duo Ivan Martic and Bosko Jankovic were replaced by Frederik Sorensen and Juanito.
Sorensen almost headed a spectacular own goal, but was relieved to see goalkeeper Rafael make a smart stop.
Veteran striker Toni, who scored twice in a 4-1 Verona win when the sides met in this fixture last season, looped a header over the bar and that warning shot went unheeded as the hosts levelled in the 69th minute.
Cavanda, having been carded five minutes into the second half, pulled on the hand of Juanito and Toni seized on the opportunity to level from 12 yards.
Lazio survived a late scare when Juanito fired over from a good position, with the spoils shared.
