With second-placed Rangers in cup action on Sunday, it was a chance for the Jambos to continue to stamp their authority on the division and they did not disappoint, although they needed a desperate push in the final stages to deny their struggling opponents.
It was a frantic finale as Hearts held on after seeing Genero Zeefuik’s early strike cancelled out by Craig Sives, only for substitute Kenny Anderson to score the crucial second on his debut and Jamie Walker adding a third.
There was still time for the spirited bottom club to battle back as McKay bundled over Myles Hippolyte in injury-time to get his marching orders just minutes after coming on with Keaghan Jacobs scoring a consolation penalty.
Hearts looked to be heading for a comfortable afternoon when they deflated the mood at Almondvale Stadium as Zeefuik, on loan from FC Groningen, picked up a long punt before curling a low shot beyond ‘keeper Darren Jamieson to score his fourth in as many games.
Livingston settled impressively despite the early setback and enjoyed lengthy spells of possession with Hearts happy to sit back and soak up the pressure.
The visitors still had their chances, though, as Miguel Pallardo volleyed just over and Callum Paterson and Zeefuik both went close before the interval.
The hosts came roaring back and deservedly levelled the scores when a long throw-in fell to Sives at the back post and he fired in as the protests by the Hearts players for offside fell on deaf ears.
Both teams threw caution to the wind and created several chances after the break. Walker and Zeefuik in particular wasted opportunities but both shot wide, while Sives headed off-target for Livingston.
With time running out, Anderson was introduced and powered in a header from Billy King’s sizzling cross from the left to get his team back in front.
King was the provider again as he fed Walker the ball on the right and he raced into the box and drilled a low shot past Jamieson.
It was an enthralling finale and back came the hosts as Jacobs scored from the penalty spot after McKay’s clumsy foul on Hippolyte, but Hearts held on to stretch their lead at the top of the Championship.