The club was established in 1921 playing at Grove Corner and in 1925 joined the Western League Division Two.  Although winning this division twice before World War II, the club never achieved promotion to Division one.  They regularly played in front of crowds of two and three thousand – a period when they were virtually unbeatable at their Grove Corner ground.  During this period, the club won the Dorset Senior Cup on four occasions and the Dorset Amateur Cup three times.

Following World War II, the club turned semi-professional and re-joined Division One of the Western League, where they remained for the next 24 seasons.  During this time the ‘Blues’ lifted the Dorset Senior Cup a further six times.  The record attendance at Grove Corner was set in January 1949 when 4,127 watched the League match against neighbours Weymouth – which Portland won 4-1.

The most successful season in the club’s history came in 1965/66 when they finished as runners-up in the Western League Division One and progressed to the 4th Qualifying Round of the FA Cup where they held Yeovil Town to a 1-1 draw at Grove Corner in front of a crowd of 3,069.  In the replay at the Huish, in front of 6,005 spectators, the ‘Blues’ were beaten 3-1.

In 1994 the Crown decided it needed the original ground for mineral extraction and the club was provided with a new home a couple of hundred yards along the road – hence the name ‘New Grove Corner’!  The last game at the ground took place on 9 May 1994, when neighbours Weymouth were the visitors in front of a 500 plus crowd. It was however a far cry from the record attendance, set on 27 January 1949 when 4,127 saw Portland defeat Weymouth 4-1 in a Western League Division One match.

During the winter of their first season at the new ground, the entire island of Portland had to be evacuated whilst an unexploded wartime bomb – found underneath the penalty area of their old ground – had to be defused!

Although Portland did step up to the Wessex League in 2001, they struggled and returned to the DPL IN 2006 where they have been very successful League winners:  2007–08, 2008–09, 2012–13 and 2013-14 and runners up in 2014/15.  They also won the Dorset Premier League cup in 2008/09 finishing as runners up on 3 more occasions.

Portland’s promotion was approved by the Football Association in 2015 (new floodlights were installed) and Portland Utd FC were promoted, much to the delight of everyone connected with The Blues, to The Sydenhams Wessex Football League Division One.  The Blues won Division One in their first season, losing just 4 games in the league, amassing 84 points with a +72 goal difference from 34 games.  Portland also reached the semi final of The Wessex League Cup losing to eventual winners Team Solent in extra time, The Blues also knocked out three other Wessex Premier Division sides en route to the semi final. Portland Utd FC’s programme was also awarded Programme of the Season Award. 

The start to the 2016/17 season saw Portland Utd FC win six, lose two and draw 2 – everyone supporting The Blues were looking forward to hopefully ending up in the top ten at the end of the season.  However, following an unbeaten league run of 27 league games, Portland Utd FC had everything to play for in their last match home v Bemerton Heath Harlequins – needing all three points to have a chance of winning the league.  With the game at 1 – 1 at 90 minutes it looked like The Blues would have to settle for second place – but a 95th minute goal saw the Blues clinch victory and achieve a remarkable first season in the Premier Division under Manager, Gary Bailey.  Portland Utd FC’s programme was once again awarded ‘Programme of the Season’ and Portland also topped the highest average attendance table.