Smith is locked in a fierce leadership contest with Jeremy Corbyn, with the winner due to be announced on September 24.
The first ballot papers for the election were being sent out yesterday to the estimated 640,000 members and supporters who will be tasked with choosing between the pair.
Both candidates are expected to kick their campaigns up a gear as the race to win support intensifies.
Smith used a speech in Porth in South Wales to make a pitch to members that he will listen to their concerns.
The Pontypridd MP also sought to distance himself from New Labour governments, which he accused of hiding away from the party’s principles.
He called for a “revolution in accountability” as he reiterated a pledge to create a shadow cabinet of party members to advise the leadership, and also vowed to “turbo-charge” the party’s national policy forum. Smith then promised to empower the party’s conference.
He said: “My promise to the party is I will not ignore conference. I will bind myself to the decisions made by conference on party policy.
“I will not seek to overturn it whatever my views, but I will seek to influence it.”
He said: “Crucially, I will give conference a new role and a responsibility in our party to sign off on our manifesto.
“No Labour leader has done this before and I believe it is necessary to reassure people across the party that there will be no backsliding on my watch.”
Smith’s intervention comes after Corbyn pledged to strengthen trade union bargaining powers if he becomes prime minister.
Proposals unveiled by Corbyn include mandatory collective bargaining in firms with more than 250 employees, the election of staff representatives to executive remuneration committees, and the introduction of “sectoral union bargaining rights”.
The Labour leader said his proposed changes to trade union rights would form part of a wider package of reforms to “democratise our country from the ground up”.