The South Coast club decided to pull the plug after an abysmal run of one win in their last 17 league matches, with their most recent showing coming in the form of a 3-0 loss to fellow strugglers Newcastle United.
As it stands, Southampton currently sit one point above the relegation zone with time running out.
The Argentine was appointed last summer after the dismissal of Claude Puel, who has since found work again with Leicester City and is doing a fine job.
Pellegrino won only eight of his 34 games in charge of the Saints; a win rate of 23.5 per cent.
In the wake of the news regarding Pellegrino's sacking, many Southampton fans have been calling for Ostersunds manager Graham Potter to take the club forward.
Potter has risen to prominence with the Swedish minnows over several years, taking them from the Swedish fourth tier to the Allsvenskan after a number of successful promotions.
He and his team were crowned Swedish Cup champions in 2016/2017, the first major trophy in the club's history, leading to qualification for the Europa League knockout stages.
After defeating the likes of Galatasaray in the qualifying rounds, Potter led Ostersunds through the group, finishing top and setting up a tie against Arsenal in the round of 32.
Despite eventually being knocked out, Ostersunds recorded an emphatic 2-1 victory at the Emirates Stadium to cap off a stunning story all round, rightly leading to Potter being linked to vacant jobs back in his native land.
Here is a round up of some of the reaction from the Southampton fans:
I hope Southampton take a gamble and appoint someone like graham potter and hopefully works for them. Don’t go for same old manager like Hughes and don’t go for Silva who if does good will want to leave like with Watford #bbcfootball— Daniel Hodson (@dshodson) 12 March 2018
Graham Potter played 8 games for Southampton. Been managing Östersunds (Beat Arsenal, away, in Europa) in Sweden, gained them 4 promotions and a Swedish cup. Been doing some reading on him and he’s always willing to try new things, experiment with the team and play positive!— Hayden Forssman (@HJForssman) 7 March 2018
One thing I am pleased with is the reports linking us to Graham Potter. Have long said I think he's a real talent. I think we'd all be much more patient if there was a Long Term Appointment/Plan, rather than Just Another Coach. #saintsfc— The Archers Road End (@ArchersRoadEnd) 7 March 2018
if i were the saints board, i would go for Marco Silva or Graham Potter.— laurent w (@lrtwong) 13 March 2018
Have you seen what Graham Potter has done in Sweden? Get him in!— JAMIE HARRIS (@gardenyjamie) 13 March 2018
Graham Potter is a good shout for #SaintsFC next season, but to stay up may need his brother Harry Potter in short term— Philip Hughes (@Dubai_Phil) 13 March 2018
Give Graham Potter all the money in the world— Patrick Henderson (@Pat_Henderson15) 12 March 2018