Surjeet Chana, 64, used her position in the Land Registry office to supply essential documents to the gang, which included a solicitor, bank manager and drug traffickers.
Using information she gathered, including title deeds and ownership signatures, the group targeted empty homes, pretending to be the owners and selling them on to third parties.
Southwark Crown Court heard at least nine properties across London, worth £5 million, were sold by the gang in just two years.
Many of the houses belonged to vulnerable elderly people who had moved into nursing homes due to ill health, the court heard.
Chana, who was said to have been a respected member of the Sikh community, denied conspiracy to commit fraud by false representation but was unanimously found guilty by a jury.
Today, she collapsed in the dock as Judge Michael Grieve QC sentenced her to three years and nine months in prison.
The mother-of-three, who has previously worked with the Prince's Trust, was caught when police put other gang members under surveillance, suspecting a drug deal.
Officers overheard a conversation revealing the Land Registry plot, and searched Chana's £600,000 home in Purley.
They found £38,000 in cash hidden in the loft, which she planned to spend on an extension, and discovered she had been paid £4,000 a time for documents she provided.
She was suspended from her £21,709 job as a registration officer in Croydon, South London, following her arrest in 2010 and later sacked after 33 years of service.
Judge Michael Grieve QC said hers was a "sad case" but told her he had no alternative but to pass a custodial sentence.
He said: "This was a serious breach of trust. I accept you were corrupted but in your case your motivation was greed. I have heard from your counsel that you were in no kind of financial problems.
"You have brought great shame on yourself and your family, you have ruined your career and no doubt prejudiced your pension rights.
Judge Grieve added the gang preyed on "highly vulnerable" victims whose family homes which had a "lifetime of memories" were sold from beneath their noses.
"It takes little imagination to realise the shattering trauma that this experience would bring," he said.
Other key members of the gang were also sentenced for their involvement in the conspiracy, receiving between two and four years in prison for their offences.
Charles Spiropoulos, 48, a conveyancing solicitor from Hackney, east London, who worked for Andrews and Co solicitors, was sentenced to four years in prison, while Van Che, 24, of Brixton, south London, who found the properties, was given three and a half years.
Barry Eve, 51, Altaf Haroon, 50, and a 42-year-old bank manager, all from south London, were found guilty of money laundering.
In a statement read to the court, victim Anne McKendrick, 53, said she had moved out of her Purley home following a traumatic burglary in 2004 but had hoped to move back there one day.
She revealed her "huge loss" after police told her out she no longer owned the house she had bought in 1983.
Freda Gallacher, who late brother had been a victim, said: "The whole experience has left me in near financial ruin and certainly took its toll on my health."
After sentencing, Chana's solicitors released a statement saying she was "deeply disappointed" by the verdict.