The victory over the holders gave Donegal their second title after their first triumph two years ago.
Roisin Friel and Yvonne McMonagle hit early goals as Donegal took control.
Points by Ellen McCarron kept Monaghan in touch but McLaughlin's first goal helped Donegal lead 3-5 to 0-9 at the break and they remained in command.
Donegal's winning margin would have been even bigger but for a final goalkeeping display by Linda Martin.
Meanwhile, Galway defeated Mayo 3-12 to 1-8 in the Connacht Ladies Final at Castlebar.
SUNDAY OTHER GAA RESULTS
Munster SFC Final
Kerry 1-23 0-15 Cork
Ulster MHC Semi-Finals
Antrim 1-21 0-18 Down
Derry 4-16 2-06 Donegal
Leinster SHC Final
Galway 0-29 1-17 Wexford
Geraldine McLaughlin hit 2-6 as Donegal clinched a 4-11 to 0-15 win over Monaghan in the Ulster Senior Ladies Football Final at Clones.