The crowd spilled out of the Methodist church in the capital on Tuesday, with President Robert Mugabe and a raft of senior officials from both the ZANU-PF and Tsvangirai’s Movement for Democratic Change (MDC) in attendance.
An inter-denominational choir sang dirges as the hearse arrived and Mr Tsvangirai, dressed in black, entered the church.
The church service was to be followed by a larger public memorial at a Harare stadium, the same venue where just four weeks ago Mr Tsvangirai was cheered as the new prime minister in the unity government.
The crash and Susan Tsvangirai’s death have overshadowed the new government’s work to rebuild an economy devastated by world-record hyperinflation with more than half the population dependent on foreign food aid for survival.
A US-British aid truck carrying AIDS drugs slammed into the Tsvangirais’ four-wheel drive on Friday on a potholed highway outside Harare.
Susan Tsvangirai died instantly and Mr Tsvangirai suffered minor injuries. He was briefly hospitalised in Harare and flew over the weekend for further medical checks in Botswana, but quickly returned home to prepare the funeral.
Mr Tsvangirai has sought to dispel fears the accident could have been linked to a long history of deadly political trickery in Zimbabwe, ruling out any foul play in her death.
"It was an accident and unfortunately it took her life,” he told mourners gathered at his home on Monday.
"I want to thank God for giving me 31 years with my wife,” he said.
"Life will go on, and I am certain she would have liked life to go on.”
Her body would be taken to the couple’s Harare home later on Tuesday, before burial on Wednesday morning in their hometown Buhera, his party said.
Susan Tsvangirai, 50, generally avoided the political spotlight.
She founded a charity to teach women about AIDS, which has expanded to provide other health and social services in a nation where health care has collapsed.
The MDC is conducting its own investigation into the crash, but has not alleged foul play. Doubts about the incident eased after Washington and London said the truck was owned by a joint US-British aid project that delivers HIV/AIDS drugs.