This is the first time the minister has appeared before the committee in relation to the matter.
Mr Ó Muilleoir said he had nothing to do with the back channel of communication between a former Sinn Féin MLA and a loyalist blogger.
He has previously denied any knowledge of the coaching.
On Wednesday, he said: "What part of 'no involvement with, no part in, no knowledge of' does the committee - with all due respect - not understand?
"I had no involvement whatsoever with this particular affair - none, zilch, nada, nothing."
Before he became a minister, Mr Ó Muilleoir was one of the Sinn Féin members on the Stormont finance committee when it held a high-profile inquiry into the controversial sale of Nama's NI property portfolio.
Nama is the Republic of Ireland's "bad bank" which was established in 2009 in the aftermath of the Irish banking and property crisis.
It took effective control of a huge property loan book in Northern Ireland and formed a committee to advise on that part of its portfolio.
Nama sold its entire Northern Ireland portfolio to Cerberus, a US investment fund, in 2014.
Mr Ó Muilleoir said those who were "throwing the mud" over the Nama coaching claims "haven't been able to get any thread, any scintilla" of evidence linking him to this "disgraceful and inappropriate behaviour".
The minister has also stood firm in his post amid calls for him to step down.
In August, it was revealed former MLA and Finance Committee chairman Daithí McKay had secretly advised Jamie Bryson ahead of his appearance at the Nama inquiry.
Mr McKay apologised and resigned from his post.
Finance Minister Máirtín Ó Muilleoir has told Stormont's Finance Committee he had "no involvement" in the Nama coaching scandal.