The First Minister and SNP leader said that while any party would want to reflect on such circumstances, the process followed had been “robust”.
Ms Sturgeon has made clear her view Mr McDonald should step down as an MSP after he resigned from the SNP yesterday.
The MSP for Aberdeen Donside has apologised for causing “hurt and offence” to two women, but said he intends to stay on at Holyrood as an independent MSP.
Ms Sturgeon was asked what lessons her party could learn from the case on a visit to Portobello in Edinburgh ahead of International Women’s Day tomorrow.
She said: “I think any party who has a politician who ends up in this position will want to look reflectively at that, but I was determined, and the party was determined, to make sure that a robust process was followed.
“We ensured that the investigation was independent, that it took the time to thoroughly investigate the allegations that were made and, of course, those findings were shared with Mark McDonald earlier this week.
“I think it’s important that these processes are in place and that is what the SNP made sure of.
“Supporting women to come forward, making sure that a robust process is in place, allowing an investigation to happen and then making sure that nothing is swept under the carpet in that – I think these are things all of us have a duty, in circumstances that are very difficult and not of our choosing to be in, that we seek to do the right thing.”
SNP bosses launched an investigation into reports of inappropriate behaviour by the married father-of-two, with allegations made by three women.
The findings were shown to Mr McDonald on Monday, with investigators concluding the MSP’s inappropriate behaviour had been “deliberate in nature” and he should have known not to act in this manner.
The behaviour is said to include sending inappropriate and unwanted text and social media messages, causing distress to women through his unwanted attention and exploiting his position of power, with the investigation finding there had been “persistent behaviour over an extended period of time”.
Mr McDonald has been absent from the Scottish Parliament since the allegations against him were first made in November, but plans to return next week.
McDonald yesterday issued an “unreserved apology” to three women who complained about his behaviour and said he had been seeing a behaviour coach.
But Ms Sturgeon responded by saying: “The SNP cannot force Mark McDonald to stand down as an MSP.
“So it’s a matter for him. My view is clear - he was elected as an SNP MSP and if his behaviour was such that he himself considers that he cannot continue as an SNP MSP then it would be appropriate to give his constituents the opportunity to elect a new MSP.”
Mr McDonald’s resignation came on the eve of a scheduled disciplinary vote by his Holyrood colleagues to determine his future in the SNP group.
There is no suggestion that his behaviour was serious enough to merit a police investigation.
But his decision to remain prompted an angry reaction from opposition MSPs who questioned how his behaviour was bad enough to see McDonald quit the SNP - but not Parliament.
Tory MSP Alexander Burnett said: “Many people will rightly be questioning why Mark McDonald thinks that his behaviour was bad enough to resign from the SNP, but not to resign from the Scottish Parliament.
“He is clearly prioritising the reputation of the SNP over that of Holyrood, and it’s simply not good enough.”
Mr McDonald announced his resignation in a statement in Aberdeen where he refused to take questions.
He said his behaviour coach had made him a better person and he has been assessed as showing a “willingness to change”.
He added: “I would like to take the opportunity to offer a public and unreserved apology to those individuals for the hurt and offence that I have caused them.”
He also revealed that had sent a written apology to one of the complainers, in line with that individual’s wishes.
The behaviour was also found to be “persistent over an extended period of time”. He was also judged to have “exploited his position of power”.