The visitors had jumped out to a 14-3 lead with two quick tries of their own, both created by the boot of D'Angelo Leuila. Midfield partner Bailyn Sullivan was on hand to collect a pair of clever kicks over the top of the Otago defence, laying on one try for Damian McKenzie before scoring a second himself.
Otago pulled back a try through Josh Dickson to make it 14-10 at the break but, with a couple penalties to McKenzie, Waikato would have been confident of securing victory when they led 20-13 in the 68th minute.
That was when Freedom Vahaakolo produced what became a crucial 50-22 kick, seeing Will Tucker cross from the subsequent lineout to level the scores and set the stage for Timu, who showed good pace to race clear and dive over in the corner.
The result kept Otago right in the hunt for a quarter-final spot while Waikato remained on top of the conference ahead of their trip to contest the Ranfurly Shield in a top-of-the-table clash against Wellington next weekend.
Bay of Plenty moved clear in third behind those two sides by thumping the winless Southland in Tauranga. The Steamers blew away the visitors with five first-half tries, including a brace for winger Emoni Narawa, as they took a commanding 33-7 lead to the break.
And although Southland showed some fight in the second spell, it was nowhere near enough to prevent a 54-21 defeat, with the Stags' eighth straight defeat compounded by the season-ending shoulder injury suffered by Marty Banks.
Later in the afternoon, North Harbour thumped Northland 48-21 in Whangārei, leapfrogging the Taniwha in what could prove a pivotal victory in the playoff race.
A couple of weeks removed from upsetting Auckland, Northland initially looked like they could take down another of their Super Rugby partners, capitalising on North Harbour mistakes to score three tries and trail 27-21 at halftime.
But after forcing Harbour to do plenty of defending to begin the second spell, Northland were unable to add to their tally and were soon taught a lesson in being clinical. The visitors broke open the game with Shaun Stevenson's second try and, leaning on a productive counter-attack, proceeded to score two more as the fullback completed his hat-trick after the hooter had sounded.
Otago 27 (Josh Dickson, Will Tucker, Josh Timu tries; Cam Millar 2 pens, 3 cons)
Waikato 20 (Damian McKenzie, Bailyn Sullivan tries; McKenzie 2 cons, 2 pens)
Halftime: 10-14