First half goals from Hernanes and Rodrigo Palacio had put the Nerazzurri firmly in the driving seat. Paulinho and Innocent Emeghara replied after the break to peg Inter back and hand Livorno a relegation lifeline.
The result keeps Inter in the Europa League places in fifth, although a whole host of teams are within range of catching them. Their winless run stretches to three games. Livorno stay in the drop zone, although they are just a point adrift of safety.
Inter were fresh from being jeered off the pitch following Thursday's goalless draw against Udinese. As a result, Walter Mazzarri adjusted to a more attacking 3-4-3 formation and made four changes to his starting lineup. Rolando, Zdravko Kuzmanovic, Danilo D'Ambrosio and Ricky Alvarez all came in for Andrea Ranocchia, Esteban Cambiasso, Yuto Nagatomo and Fredy Guarin.
Hernanes and Jonathan both sent early shots off target for the visitors. It was Livorno who forced the first save of the match on 16 minutes when Samir Handanovic clawed an Emerson free kick out of the top corner.
Kuzmanovic continued Inter's trend of failing to hit the target with another wayward effort. Meanwhile, Paulinho tested the Inter defence with a darting run into the box, forcing Walter Samuel to get a crucial block in.
Hernanes finally started to find his range. The Brazilian bent a left footed shot which beat Francesco Bardi, but not the far post. Belfodil failed to get enough contact on a header to trouble Handanovic, before a dangerous Hernanes cross found the head of D'Ambrosio at the far post. Luckily for Livorno, Bardi had rushed out of his goal to close the angle.
Hernanes finally opened his Inter account eight minutes before the break. Palacio cushioned an Alvarez cross and Mauro Icardi's mis-hit fell kindly for the former Lazio man to smash the ball in from four yards.
Two minutes before the break, Livorno's defenders backed off Kuzmanovic as he surged towards goal. Bardi tipped the Serbian's vicious shot over.
Inter doubled their advantage in first half stoppage time. Palacio was left all alone at the far post, volleying Jonathan's cross into the ground and beating Bardi at the far post.
Palacio almost doubled his tally just 18 seconds after the restart. The Argentine latched onto a through ball and Bardi saved smartly with his legs.
Livorno halved their deficit on 54 minutes. Paulinho peeled off his markers to meet a short corner and blast a shot off the bar inside the top right corner.
Alfred Duncan and Emeghara were introduced to try and unsettle the Inter defence, as the Amaranto naturally poured forwards looking for an equaliser. However, it was Inter who remained more dangerous. Hernanes saw a shot charged down and Rolando failed to direct a header towards goal from a free kick.
Benassi was denied a penalty 15 minutes from the end when he went down under a Juan Jesus challenge. Replays showed minimal contact, with Benassi going to ground a little too easily.
Inter should have made the game safe moments later. Icardi sprung the offside trap and laid off for Guarin. The substitute ran into heavy traffic in the box and eventually dragged his shot into the side netting.
Livorno were dealt a blow when they were forced to play the final 12 minutes a man down. Mbaye limped off and all three substitutions had already been made, making the home side's task that bit more difficult. Remarkably, the ten men pulled a rabbit out of a hat and found an equaliser five minutes from time. Emeghara seized on Guarin's poor backpass and outpaced Samuel to slide the ball past Handanovic.
Inter threw everything forward. Bardi denied Kuzmanovic at the far post and Icardi headed one final chance over, as Livorno held on.
Livorno: Bardi; Valentini, Emerson, (Duncan 55) Castellini; Mbaye, Benassi, Biagianti, Greco, (Siligardi 73) Mesbah; Belfodil, (Emeghara 55) Paulinho
Goals: Paulinho 54, Emeghara 85
Inter Milan: Handanovic; Rolando, Samuel, Juan Jesus; Jonathan, (Zanetti 79) Hernanes, (Guarin 69) Kuzmanovic, D'Ambrosio; Alvarez, (Botta 86) Palacio; Icardi
Goals: Hernanes 37, Palacio 45