Since that feat, the Tykes have found themselves slumped at the opposing end of the division, and on two occasions, were relegated to Sky Bet League One.
From relegation candidates to play-off hopefuls, Barnsley have had quite the upturn in fortunes since the conclusion of a divergent campaign in the football calendar last July.
A huge sigh of relief
Despite causing a huge shock on the opening day of the 2019/20 season with a 1-0 home victory to Scott Parker's Fulham side - Barnsley endured a torrid start to the campaign.
An opening day victory over the Cottagers was just one of only two wins in their first 20, which laid the foundations for a difficult season ahead.
A Barnsley side, then managed by Gerhard Struber, found themselves marooned at the bottom of the division, and seven points from safety when the first national lockdown was called into action last March.
The three-and-a-half month break seemingly allowed Barnsley to reinvent themselves, yielding 15 points from a remaining 27, including back-to-back victories against promotion hopefuls Nottingham Forest and Brentford in the final two fixtures of the 46 game Championship marathon.
A fantastic victory in the penultimate game at Griffin Park continued the Tykes tremendous run of form, however, it remarkably left them in limbo as to what division they would be playing their football in the following season.
Mathematically Barnsley were relegated to League One, but due to off-the-field issues hampering the club - Wigan Athletic were condemned to a 12 point deduction, which saw them drop below the Tykes into the drop zone, despite a comfortable 13th place finish under manager Paul Cook.
Investing in youth
It's clear for all the see that Barnsley have added vigour and energy to their squad, revitalising it with youthful talent that are always keen to impress, as well as improve.
With a first team squad of 24 players, the Tykes boast an average age of 23.6, which is a figure that's unsurprisingly the lowest of any in the Championship.
Dominik Frieser came in as the club's oldest summer signing - at 26. The German international joined from Austrian side LASK and the versatile midfielder has chipped in with two goals and two assists since his arrival in South Yorkshire.
Frieser was the anomaly in a summer transfer window of young arrivals, however, these additions alongside the huge improvement of other individuals already contracted to the Tykes, is one of the big factors in a welcomed upturn of form for Barnsley.
Mads Juel Andersen evidently struggled adapting to English football in his first season at the club, with a string of mistakes and poor performances leaving a lot to be desired among the Barnsley faithful.
Fast forward one year and Andersen has been a pivotal figure in the Tykes back line. The Danish international has started every single Championship fixture for Barnsley this season and deserves immense praise for his all-round improvement as a defender.
20-year-old Callum Styles is another youngster that has stepped into the limelight this season and put in a catalogue of impressive performances.
The tricky winger started just five matches last campaign, but like Andersen and many of his fellow professionals, has grown into the role and excelled this season.
Styles has been a nightmare to handle for Championship full-backs at times this term, and with a seemingly bright future ahead of him, Barnsley will be keen to bat off any inevitable interest surrounding the bright young winger this summer.
A huge setback
Although the table at the time didn't reflect an amazing job, former boss Struber was at the helm to oversee Barnsley's 2018/19 promotion from League One and was a likeable, well-received figure at Oakwell.
For the outsider looking in Barnsley were lucky and scrapped their way to safety, however, scratch beneath the surface and you unveil a well drilled team that were unlucky not be flying higher in the division under a determined coach that implemented a high pressing style.
After 11 months in charge, Barnsley announced Struber would be walking away from his role after a contractual agreement was met by American side - New York Red Bulls.
The ideal replacement
You can be forgiven if you didn't know all too much about Valerien Ismael's background in management prior to his arrival at Barnsley, nevertheless, since taking the reins in October 2020 he has impressed.
In late 2011, Ismael began his career in first team management with Hannover 96 II and the 45-year-old remained in Germany for another six years until 2017 - managing a further three different teams.
Despite coming into the job as an unknown, Ismael has worked well with the squad he inherited and has also bought into the clear philosophies of keeping a low average squad age. The Frenchman delved into the market for three players in the recent January transfer window, bringing in Carlton Morris (25), Daryl Pike (20), and Liam Kitching (21).
Ismael announced when taking the job that two big factors were his desire to manage in the English game, as well as the Tykes matching his preferred play style.
The former Bayern Munchen midfielder has now taken charge of 24 matches as Barnsley boss and across that time he has tasted victory 13 times - accumulating a 54.43% win ratio.
Are the play-offs a realistic target?
The top-half of the Championship table is unfamiliar territory for Barnsley, but is sure to be one they will like adapting too.
From closing down teams outside of the drop zone to chasing the missed opportunities of fellow play-off hopefuls within the space of a year - are Barnsley realistic contenders for a top-six spot?
A quick glance over the table and you will find Barnsley in 12th position, however, in a closely contested mid table battle, league positions and end of the season ambitions are changing every week.
Besides Blackburn Rovers, the Tykes have games in hand on all of the teams around them, and if Ismael's side prevail in that re-arranged fixture with a struggling Derby County, they will move to within just four points of AFC Bournemouth - who occupy the final play-off spot in sixth.
Alongside the names previously mentioned, Michal Helik will be keen to continue his impressive season alongside Andersen, as well as key figures Alex Mowatt and Cauley Woodrow - whose performance levels will be instrumental to the Tykes success.
With months to go until the final knockings of the season, the Championship is likely to throw up its crazy and enthralling annual surprises. But after years of mediocre and below par finishes, Barnsley will be hopeful they can be a part of the drama at the top end of the division, as they cruise towards their best league finish in 17 years.