Jackson is Gillingham's top scorer this season with 20 goals
Two goals from Simeon Jackson helped Gillingham to overcome Rochdale and set up a clash with Shrewsbury in the League Two play-off final.
Jackson's first gave Gillingham the lead, nipping in at the near post to convert an Andy Barcham cross.
Chris Dagnall brought Rochdale level when he turned Gills defender John Nutter and fired home from 10 yards.
Jackson had the final word though, scoring from the spot after Nutter had been fouled by Dale's Rory McArdle.
Rochdale were seeking their second successive play-off final - having lost 3-2 to Stockport County at Wembley last season - but it is Gillingham who keep their dream alive of an instant return to League One following last season's relegation.
The first leg - a 0-0 draw at Spotland - was a tight affair, and the second leg was no different.
Barry Fuller signalled the home side's positive intent from the off with a 30-yard strike but unfortunately for the Gills it was a good 15m over the bar.
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However, Gillingham did not have to wait long to take the lead when Dennis Oli released Andy Barcham down the left and his low cross was finished by Jackson, getting ahead of his marker at the near post.
At times in the first half Rochdale played some neat football, and in Dagnall they possessed a determined and willing runner up front, but too often the final ball was lacking.
However, with 35 minutes on the clock the visitors were level and it was Dagnall who scored it.
Lee Thorpe made a nuisance of himself in the Gillingham box before the ball fell to Dagnall who turned inside Nutter and fired home.
Ten minutes into the second half Gillingham were awarded a penalty when Barcham played in the marauding Nutter who was crudely felled by McArdle.
Jackson stepped up and whipped the ball into the right-hand side of the goal as Dale keeper Frank Fielding dived left.
Garry Richards almost made it three for Gillingham minutes later when he headed Nutter's free-kick against the crossbar.
Rochdale threw everything they could at the home side, including introducing top-scorer Adam Le Fondre from the bench, but the closest they came was a misdirected McArdle header from a Jason Kennedy cross.
Gillingham had a moment of deep anxiety three-and-a-half minutes into injury-time when William Buckley found space in the box to shoot but his effort flashed across goal and harmlessly wide.
Gillingham manager Mark Stimson:
"I'm very happy for the players. They've put a lot of hard work in this season.
"The majority of them came back on the first of June - some of them weren't too happy because I cancelled a lot of their holidays, but you get your rewards if you're prepared to do that little bit more.
"Now they've got their big reward by going to Wembley against a good Shrewsbury side we know about and we look forward to it."
Rochdale manager Keith Hill:
"There's a lot of emotions in that (dressing) room because we weren't expecting to go out tonight.
"There's a lot of soul-searching to be done throughout the course of the summer.
"Not just from me and Flicker (assistant boss David Flitcroft), but from the board of directors, the chairman and the players themselves."
Royce, Fuller, Richards, King, Nutter, Lewis, Wright (Bentley 71), Weston, Barcham, Oli (Southall 84), Jackson (McCammon 90).
Subs Not Used: Julian, Jarrett.
Jackson 13, 58 pen.
Fielding, Ramsden, McArdle, Stanton, Kennedy, Thompson (William Buckley 61), Toner, Gary Jones, Rundle (Le Fondre 69), Dagnall, Thorpe (Shaw 68).
Subs Not Used: Mark Jones, Holness.
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