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.
Wales should be central in the debate on the UK union and devolution, Welsh Secretary Stephen Crabb has insisted.