Linda Box, 67, was jailed for seven years today after a court heard she stole from client accounts at Wakefield-based Dixon, Coles and Gill.
Box was a senior partner at the historic firm and abused her position to fund a lavish lifestyle for herself and close family members.
She also took advantage of her role as a "pillar of the church" when she was registrar with the Diocese of Wakefield.
Box stole £63,000 of Church of England cash belonging to the Bishop of Wakefield's Fund.
Leeds Crown Court heard the total value of the 12-year deception was £4,055,329.
Box used the money to fund for her "obsession" for buying clothes, including holding a special account cars with Harrods.
Money was also spent on £800-a-night stays at the The Ritz in London and a collection of vintage wines for her son worth £800,000.
Sums of illegally obtained cash also went on funding mortgages for relatives, private school fees for her grandchild and landscaping work at her home.
Other spending included holidays abroad. On one occasion £11,000 was spent to pay for her family to go to the Edinburgh Festival.
Box also paid £236,554 to a marketing and public relations firm which did work for her husband's firm of funeral directors.
Illegally obtained cash was also used to cover her tax liabilities and pay council tax bills.
Box also forged the signature of another solicitor on probate documents as part of her offending.
She forged the signature of another colleague in order to access a trust fund.
Box, of Halifax Road, Dewsbury, pleaded guilty to nine counts of fraud, two of forgery and one of theft.
The firm, which had offices in Wakefield and Horbury, shut is doors in January last year after more than 200 years of practising law after a fraud investigation was launched by police.
The Solicitors Regulation Authority stepped in four months later to formally prevent the firm from operating.
The court heard the Dixon, Coles and Gill building had now been sold off and staff had been made redundant as a result of Box's offending.
Nadeem Bashir, prosecuting, said the offending came to light in December 2015 when another partner, Julian Gill, conducted a review and became concerned over a £5,000 payment from a client account.
Further checks revealed sums had been paid out of client accounts on a wider scale, including payments to Box's American Express card account.
Police were contacted when it was revealed that over one million pounds was identified as being stolen.
The investigation also uncovered Box's offending while she was registrar and legal adviser to the Diocese of Wakefield.
Part of her role included looking after church funds.
Details of transactions in Box's handwriting were found in a ledger book which purported to have been done on behalf of the Bishop of Wakefield Fund.
A total of £63,787 was paid from the fund into her own bank account.
Some 75 individual client files, many involving estates of deceased, and ten files relating the church showed misappropriation.
Box was interviewed by police and admitted taking the money for her own personal use. She said her husband did not know about the offending.
Mr Bashir said: "She said she was excessive in her spending. She said it developed into an obsession."
The prosecutor said victims of Box's offending had been left devastated at the abuse of trust.
He added: "The consequences are enormous."
Jailing Box, Mr Justice Blake said it was a tale of misplaced trust “all because of your unrestrained and out of control greed.”
The judge said the scale and enormity of the breach of trust which was “staggering” and she had "fobbed off" anxious relatives.
The mother of one deceased client said: “How can there be a more vile crime than pretending to be my friend when I was obviously overwhelmed with grief.”
She was considered a pillar of the church and totally trustworthy.
Joe Hingston, for Box, said: “Through me she has asked to express her complete remorse for what she has done and she recognises the devastating impact of her behaviour, the wholesale breach of trust and as much as she is able she will make every endeavour to compensate the victims in this case.
She had already been struck off after more than 40 years as a solicitor. “Her reputation lies in ruins. This was a course of conduct which simply spiralled out of control.”