Former Cabinet minister Stephen Crabb, who was facing allegations of inappropriate conduct, has been cleared of breaching party rules.
Another Tory MP, Chris Pincher, was also cleared by he panel, which was headed by an independent QC, of breaching the Conservatives' code of conduct.
Westminster has faced a wave of sleaze allegations since October, with Mr Crabb reported to have admitted sending explicit messages to a 19-year-old woman he interviewed for a job.
The party found that while Mr Crabb's behaviour fell short of the party's standards and was "inappropriate", it "did not constitute harassment".
Mr Pincher voluntarily stood down from the Whips' Office and referred himself to the Tory complaints procedure, following Mail on Sunday reports that he had been accused of making an unwanted pass at former Olympic rower and Conservative activist Alex Story.
Mr Pincher, the MP for Tamworth in Staffordshire, told the newspaper in November: "If Mr Story has ever felt offended by anything I said then I can only apologise to him."
Referring to Mr Crabb's case, a Conservative Party spokesman said: "Following an investigation, a panel headed by an independent QC has concluded that Mr Crabb's behaviour did not constitute harassment.
"However, it found that his behaviour in this matter was inappropriate and fell short of the standards the party expects.
"The party chairman has reminded Mr Crabb of the need to adhere to the spirit and letter of the code of conduct at all times. He accepted this unreservedly and has made a full apology."
On Mr Pincher, the spokesman said: "Following media allegations, Chris Pincher referred himself to our code of conduct.
"Following an investigation, a panel headed by an independent QC considered the evidence and has concluded there has not been a breach of the code of conduct."