Willie Rennie said there had been a "major shift of gravity" towards increasing the powers of the Scottish Parliament and argued that people who vote No in the independence referendum should take comfort from that.
Mr Rennie was speaking before the launch tomorrow of an updated report from Sir Menzies Campbell MP on what he described as the "growing consensus" on the issue.
The Campbell II report will draw together the arguments of other parties and set out a time-scale under which constitutional change could be delivered if independence is rejected.
Speaking to the BBC's Sunday Politics Scotland programme, Mr Rennie said: "There has been a major shift of gravity and I think now it is inevitable that we will get more powers.
"People like the Scottish Parliament but what they know is there's something missing, and what is missing is the ability to raise and set our own taxes so that we not only decide how to cut up the cake but we also determine the size of the cake."
Labour's devolution commission is preparing to publish its final report on more powers for Holyrood at the party's conference this month, while a working group is examining the issue for the Scottish Conservatives.
Mr Rennie said: "I think it will become apparent as we move forward when the Conservatives and the Labour party publish their proposals, alongside Reform Scotland and the IPPR which have also published similar proposals to ourselves, it will become absolutely clear that everybody is heading in the same direction.
"I think it's clear that the change, the shift in the centre of gravity in this debate, now means that we are going to get more powers.
"People who vote No in the referendum should know with comfort that more is yet to come."
Sir Menzies chairs the Liberal Democrat Home Rule Commission which published its vision for home rule in a federal UK in October 2012, advocating a substantial transfer of financial and constitutional power to Holyrood.
Speaking ahead of the launch of the report in Edinburgh, he said: "This is a momentous opportunity to grasp the growing consensus on more powers.
"In the event of a No vote in 2014, we can move swiftly towards delivering what we know that majority of people in Scottish wish to see. That is, a stronger Scottish Parliament within the United Kingdom family of nations."
A spokesman for Deputy First Minister Nicola Sturgeon said: "The LibDems have been promising Scotland Home Rule for well over 100 years. Their failure to deliver it - even when they were in government - shows how little commitment they have to more powers for Scotland.
"They had a perfect opportunity to prove their commitment after the 2011 election. Instead they failed to support the new powers the Scottish Government asked for, and even opposed them, thus showing no one can trust a word they say.
"The LibDems' offer falls short of what Scotland needs on three grounds - substance, the lack of a common plan, and the absence of any guarantee on delivery.
"Only a Yes vote now guarantees that the people of Scotland will be in the driving seat of more powers rather than leave the decisions that affect our lives to the whims of Westminster politicians."