Pompey won the Checkatrade Trophy on penalties following a 2-2 draw with Sunderland at a packed Wembley Stadium.
They were poor in the first half and an Aiden McGeady free-kick meant the Black Cats deservedly led at the interval.
But the Blues were rejuvenated following the restart and Nathan Thompson levelled to ensure an additional 30 minutes.
Jamal Lowe then struck to seemingly secure the win, only for McGeady to scramble the ball home at the death.
That meant a dreaded shoot-out, but Pompey scored all of their spot-kicks, meaning that Craig MacGillivray’s save from Lee Cattermole allowed Oli Hawkins to fire home the winner.
Kenny Jackett made one change from the side that won at Shrewsbury in the league the previous week.
Ronan Curtis was fit enough to start after recovering from severing his finger, meaning that Gareth Evans dropped to the bench.
The teams emerged to a vociferous atmosphere created by a packed crowd at the national stadium.
Pompey’s contingent were whipped up by rousing pre-match speeches from former Fratton heroes David Norris and Hermann Hreidarsson.
But it was the Black Cats who made the brighter start, with Thompson forced to clear George Honeyman’s teasing cross behind.
Lee Brown then made a great challenge right in the corner to stop Lewis Morgan’s charge, as the side from the north-east looked threatening.
Lowe tried his best to cause problems at the other end, although a ball into the box flew straight into Jon McLaughlin’s grasp.
Sunderland were looking more likely to open the scoring and Matt Clarke threw himself in the path of McGeady’s strike.
Pompey's best opportunity came when Omar Bogle was felled on the right and Brown swung the ball into the mixer.
Christian Burgess rose at the back post, but could not get enough power on his header to trouble McLaughlin.
An effort from Morgan was deflected behind by Brown, while a key Clarke challenge halted Will Grigg’s charge.
There was a rare shot for Pompey on 22 minutes, although Curtis’ effort was always swerving wide of the post.
Then, after Tom Naylor had conceded a free-kick, the midfielder had to nod behind Grant Leadbitter’s delivery.
Sunderland came close to breaking the deadlock soon after when the ball was only cleared as far as Morgan outside the box.
The winger hit a fierce volley that flew through a sea of bodies, but MacGillivray got down well to push the ball clear.
It was only a brief respite for the Blues, however, and they were undone after Thompson had conceded a foul.
McGeady was brought down and picked himself up to curl the ball home, albeit with the help of a deflection off Clarke’s shoulder.
Half Time: Pompey 0 Sunderland 1
Pompey tried to hit back after the break and when Bogle met a corner from Brown, his header was cleared from the line.
It would not have counted, though, as referee Dean Whitestone had spotted a foul on Luke O’Nien in the build-up.
The Blues were looking a lot brighter and trying to use Lowe as an outlet, but were still lacking a final ball.
Jackett tried to shake things up on 56 minutes, with Curtis being brought off and replaced by Evans on the left.
And it was a long pass from the newcomer that almost provided an equaliser just past the hour mark.
The ball was nodded down by Lowe and Pitman took one touch before hitting a neat half-volley that struck the base of the post.
Pompey were suddenly looking a real threat and when Sunderland failed to deal with another Evans delivery, Thompson was unable to find the target at the back post.
Lowe then had a great opportunity following good work from Pitman, but rolled his shot wastefully past the post.
Jackett made his second switch to the forward line on 69 minutes, as Bogle made way for Hawkins.
The striker was soon having his shirt tugged inside the area, although Whitestone did not think it was enough to warrant a penalty.
Evans then did well to hold off a challenge and burst forward, firing in a long-range strike that flashed past the post.
But Pompey did find themselves level on 82 minute – and the goal came from a very unlikely source.
THOMPSON had yet to score in 69 appearances, but certainly picked the right location to open his account, nodding home after Evans had collected the ball from Clarke and sent it into the box.
The Blues contingent of an EFL Trophy record crowd of 85,021 erupted as the players ran towards them in celebration.
It had been a dominant second half display, but Sunderland might have secured victory in stoppage-time when Denver Hume skipped through and sent a dangerous ball across the face of goal.
Full Time: Pompey 1 Sunderland 1
There were, unsurprisingly, a few tired legs on display at Wembley as the extra period of 30 minutes got started.
Pompey were still looking to get forward and Evans was tackled inside the box after playing a neat one-two with Brown.
Lowe then screwed a shot wide after Hawkins had laid the ball off, while an angled effort from Brown was comfortable for McLaughlin.
Following a brief break after the first set of 15 minutes, the Blues got straight back on the attack and Evans had a shot blocked after cutting in from the left.
Jackett was forced to make a change when Ben Close limped off and his replacement almost scored within seconds of coming on.
Anton Walkes received the ball on the edge of the box and his effort had to be clawed behind by McLaughlin.
But Pompey did go ahead on 114 minutes and it was a brilliant finish from LOWE, who collected a long Clarke pass and sent a glorious lob over McLaughlin and into the net.
The winger was booked for taking his shirt off in celebration, but it looked like being the decisive goal.
Sunderland had other ideas, however, and in the dying seconds McGeady scrambled home an equaliser, despite the best efforts of Clarke to clear from the line.
After Extra Time: Pompey 2 Sunderland 2
A penalty shoot-out is always a nervy occasion, but the Blues kept their nerve throughout, scoring all five of their spot-kicks.
Evans, Pitman, Brown and Lowe all tucked away their efforts, while Sunderland’s second from Cattermole was saved by MacGillivray.
It meant that Hawkins had the chance to win it for the Blues and he made no mistake, slotting the ball home to send the large travelling contingent home in joyous mood.
Pitman then led his side up the Wembley steps to collect the Checkatrade Trophy and send those fans wild with delight.
Pompey (4-2-3-1): MacGillivray; Thompson, Burgess, Clarke, Brown; Naylor, Close (Walkes 113); Lowe, Pitman (c), Curtis (Evans 56); Bogle (Hawkins 69)
Goals: Thompson 82, Lowe 114
Booked: Curtis, Evans, Lowe
Subs not used: Bass, Haunstrup, May, Vaughan
Sunderland (4-2-3-1): McLaughlin; O’Nien, Flanagan, Baldwin, James (Hume 88); Leadbitter (Wyke 95), Cattermole; Morgan (Gooch 73), Honeyman (c), McGeady; Grigg (Power 77)
Goals: McGeady 38, 119
Booked: Baldwin, McGeady
Subs not used: Ruiter, Dunne, McGeouch
Referee: Dean Whitestone