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Amy Wilson Hardy went over in the corner as England scored from their only chance in the first half.
Ireland could not breach England's solid defence and were made to pay as the world champions ran in four tries.
Forwards Laura Keates and Amy Cokayne extended the visitors' lead before backs Emily Scarratt and Lydia Thompson rounded off the win with fine tries.
With the under-20 men's side having won a Grand Slam earlier on Friday, England's men will look to complete a hat-trick by beating Ireland in Dublin on Saturday.
The women, who return to Ireland in the summer to defend their world title, have won their first Six Nations title since 2012.
Wing Wilson Hardy completed a fine England move in the 16th minute, but then Ireland dominated play.
Centre Sene Naoupu came within a metre of going over but was stopped by a superb tackle from flanker Marlie Packer, and home captain Paula Fitzpatrick was prevented from touching down by a posse of England players.
England regrouped after half-time and extended their lead when replacement prop Keates drove over the line from two metres out.
Ireland were reduced to 14 players two minutes before the hour when substitute Mairead Coyne made a deliberate knock-on.
Hooker Cokayne burst through to increase England's advantage but Ireland hooker Leah Lyons responded to give Ireland hope.
However, Scarratt finished off an excellent England move to put the result beyond doubt and then replacement winger Thompson showed her pace to score England's fifth try.
Ireland: Flood, Tyrrell, Murphy, Naoupu, Miller, Stapleton, Muldoon; Peat, Lyons, Egan, Spence, Reilly, Griffin, Molloy, Fitzpatrick (capt).
Replacements: O'Connor, Van Staden, O'Reilly, Cooney, Fryday, Healy, Caughey, Coyne.
England: Waterman, Wilson Hardy, Scarratt, Reed, Wilson, Scott, Mason; Clark, Cokayne, Lucas, Taylor, Millar-Mills, Matthews, Packer, Hunter.
Replacements: Fleetwood, Cornborough, Keates, Cleall, Noel-Smith, Blackburn, Burford, Thompson.

The boys, then aged 10 and 11, lured their victims to a ravine and carried out a "sadistic" attack in Edlington, near Doncaster, in 2009.
They were sentenced to five years' detention in 2010 and granted anonymity until the age of 18.
The High Court has now given them lifelong anonymity on the grounds they would be "at serious risk of attack".
Live updates on this story and others from South Yorkshire
The boys were released earlier this year after a decision by the Parole Board, but lawyers sought an injunction to extend their anonymity as one of the boys approached his 18th birthday.
The brothers claimed that to identify them would breach various sections of the Human Rights Act.
The High Court ruling places them alongside only four other individuals who have lifelong anonymity orders in place:
The brothers' victims, aged nine and 11, were throttled, hit with bricks, made to eat nettles, stripped and forced to sexually abuse each other in the attack.
A sink was dropped on the older boy's head, and the younger boy had a sharp stick rammed into his arm and cigarettes pushed into the wound.
Parts of the attack were recorded on a mobile phone.
The brothers had moved to Edlington just three weeks before the attack to live with foster parents.
Sentencing them at Sheffield Crown Court, Judge Justice Keith said they had committed the "prolonged, sadistic" crimes for no other reason than they got "a real kick out of hurting and humiliating" their victims.
England completed a Women's Six Nations Grand Slam by beating a physical Ireland 34-7 at rainy Donnybrook.
[NEXT_CONCEPT]
Two brothers who tortured two other children in South Yorkshire have been granted lifelong anonymity.