Sir Ed Davey has promised to be "the voice of nine million carers" in his first speech to the Liberal Democrat conference as party leader.
Speaking via video link, he drew on his experience of looking after his mother and later his disabled son.
Sir Ed also acknowledged the party's "three deeply disappointing elections" and said voters thought it was "out of touch" with their concerns.
The Kingston and Surbiton MP was elected party leader in August.
In a speech delivered online due to social distancing restrictions, Sir Ed pledged to "stand up for carers".
He recalled, as a teenager, nursing his mother when she had bone cancer and "taking her tumblers of morphine" before going to school.
He also told the audience about looking after his own severely disabled son.
"John is 12, he can't walk by himself, he was nine when he first managed to say 'Daddy'," he said. "John needs 24/7 care - and probably always will.
"So let me say this, to all of you who need care... I understand what you're going through and I promise you this: I will be your voice. I will be the voice of the nine million carers in our country."
This was a deeply personal speech from Sir Ed Davey. With Covid restrictions putting paid to a crowded conference hall, he spoke into a lone camera as he conveyed his experience of caring for first his mother, and later his son.
The still-new Lib Dem leader needs to demonstrate who he is, as well as what his party now stands for. Even after years in Parliament and a spell as minister in the coalition cabinet, Mr Davey is not a household name.
He acknowledged the challenge the Lib Dems face after three poor election performances.
One sign of a shift in direction: there was barely any mention of Brexit - a marked change for a party that put it front and central of the last election campaign.
Sir Ed spoke of the need to change approach, if not values, promising to listen. His challenge is convincing the public to hear what he has to say.
On Brexit, Sir Ed said his party would "always be European" but needed to listen to voters following poor election results.
"At the national level at least, too many people think we're out of touch with what they want. The answer is to listen to what people are really telling us and to change."
During the 2019 election, the party adopted a strong anti-Brexit message, but an internal report later argued the stance had "alienated large chunks of the population".
'We'll oppose IndyRef2'
Looking ahead to Scottish Parliament elections next May, Sir Ed said it was "imperative" that Liberal Democrats are elected to Holyrood.
The SNP government in Scotland has said it wants to hold a referendum on independence as soon as possible.
Sir Ed warned that the Scottish elections "could well determine if our country has a future", adding: "Once again, the forces of nationalism threaten to tear our family of nations apart."
In an interview with the BBC later on Monday, he further emphasised his party's opposition to Scottish independence, saying it would "vote against a second referendum every time".
The Liberal Democrat leader also used his speech to attack the government over its handling of coronavirus, accusing the prime minister of "not rising to this challenge".
He set out how he thought the UK economy should adjust to not only the pandemic, but also climate change and Brexit.
"So if there's less demand for office space, let's work with businesses to turn those buildings into sustainable, affordable homes to help solve the housing crisis," he said.
"If there's less demand for oil and gas, let's work with industry to transition the UK into the world leader in clean energy technologies - from hydrogen for heating to tidal for power."
Speaking to the BBC, Sir Ed promised to make his party, which has in the past been criticised for being male, middle-class and white, the "most diverse" in UK politics.
He added that seven of its 11 MPs were women.
Sir Ed became leader of the Liberal Democrats in August in a leadership contest triggered by the resignation of Jo Swinson.
She stepped down as leader following disappointing results in the 2019 election, in which she lost her own parliamentary seat.
As well as its MPs, the party currently has five members of the Scottish Parliament and one assembly member in the Senedd.