The Conservative minister said he was inviting other political parties for talks on securing "the best possible devolution settlement for Wales".
A new UK cabinet committee chaired by Commons Leader William Hague will now meet for the first time on Wednesday.
Mr Crabb's comments come as Wales' First Minister Carwyn Jones called for a convention on future of the UK.
Speaking on Tuesday at the Labour Party conference, Mr Jones said the union cannot be rebuilt through conversation between only Westminster and Scotland.
Now the Welsh secretary has pledged to keep Wales at the discussion table on the future of devolved powers across Britain.
Mr Crabb said he had already held preliminary discussions with Mr Hague, a former Welsh secretary himself.
"We are both in absolute agreement that Wales should be central to the debate that is now commencing," said Mr Crabb.
"I want us to use this opportunity positively to look again at how we secure the best possible devolution settlement for Wales.
"I want to move forward in a realistic, open-minded and pragmatic way."
Mr Crabb has written to the leaders of other Welsh parties at Westminster inviting them to a Wales Office "summit" to discuss "how we deliver devolution that works for Wales".
The meeting is likely to take place when parliament returns next month.
He said he is also arranging meetings with party leaders in the National Assembly to ensure their views feed into the debate.
The comments from Mr Crabb came as Prime Minister David Cameron hosted discussions with backbench Tory MPs at his Chequers country residence.
One of the two Welsh MPs to attend was the Aberconway MP, Guto Bebb.
He said events in Scotland have "completely changed the nature of the debate" on devolution.
Key to Monday's talks have been the issue of "English votes for English laws", which would see Welsh and Scottish MPs excluded from voting on devolved matters in the House of Commons.
That has led to Labour Party leader Ed Miliband accusing Mr Cameron of planning to set the UK nations against each other.
But the Aberconway MP said he took a different view.
"The promises made to Scotland must be delivered upon and if they are delivered on then we are going to end up in my view with English votes for English laws and that in my view is a simple matter of fairness," said Mr Bebb.

The eight-day hearing in Ebbw Vale is examining the request to take over 250 hectares (600 acres) of common land.
Backers, including Blaenau Gwent council, have offered around 320 hectares (800 acres) replacement land.
The inquiry has heard conflicting accounts from experts over claims the circuit would damage habitats and plant life by building on the common land.
Natural Resources Wales said it was "difficult to conclude" that the replacement land was of equal value, but it was not opposing the development overall.
But an ecology report presented by the developers said there would be a "net gain" in biodiversity because the plans included work to enhance other habitats nearby - which the Gwent wildlife trust argued against.
The Planning Inspectorate for Wales will make a recommendation after the inquiry in Ebbw vale, before Welsh government ministers have the final say on whether the plans can go ahead.

Ronald Chigunwe worked for Wessex Heartbeat, which supports the cardiac centre at Southampton General Hospital.
The 40-year-old, of Breadels Field, Basingstoke, pleaded guilty to four offences of fraud and money laundering.
However, he denied four other charges of money laundering. The Crown Prosecution Service will now decide whether he should face trial.
A decision is due within the next 14 days.
The fraud was uncovered when a new chief executive took over at the charity and became suspicious after asking Chigunwe for financial information.
The chief executive's wife - an accounts expert - was asked to look at the records and discovered the fraud.
Wales should be central in the debate on the UK union and devolution, Welsh Secretary Stephen Crabb has insisted.
[NEXT_CONCEPT]
A public inquiry into plans to build a £325m motor racing circuit in the south Wales valleys has started.
[NEXT_CONCEPT]
A former financial controller has admitted stealing more than £440,000 from a hospital charity.