Therese Coffey said the Prime Minister acted in “good faith” in his decision to give the MP who has been stripped of the Conservative whip a key ministerial role.
It comes as six new claims of inappropriate behaviour by Pincher have emerged, days after he was suspended as a Tory MP after allegations he groped two men.
The allegations reported in the Independent, the Mail on Sunday and the Sunday Times include three cases where it is alleged Mr Pincher made unwanted advances to male MPs, including in a bar in parliament, and in his own parliamentary office.
Former No 10 adviser Dominic Cummings alleged Mr Johnson had referred to the MP as “Pincher by name, pincher by nature” long before appointing him in February.
However, Ms Coffey defended Johnson, stating “serious allegations” were dealt with “decisively”.
Asked if Boris Johnson was aware of allegations against Pincher when he made him deputy whip in February on Sky News, Coffey said: “I am not aware if he was made aware of specific claims.
“I don’t pretend to be part of the general rumour mill but I don’t believe he’s been in a long-term relationship but that’s as far as my knowledge goes."
Asked if she was aware of any allegations or concerns over the behaviour of Chris Pincher, Ms Coffey said she is not, adding: “I was just not part of that sort of chatter group.
"I don’t know about any individual conversations.”
Coffey went on to say she believed the Prime Minister made the decision “in good faith” as she said she thinks the leadership qualities of the Prime Minister are “very evident”.
Asked if there is a specific problem with Conservative men, Therese Coffey said: “I don’t think that’s the case at all.”
“I think there are more women MPs in parliament than ever before and I think if people approached me I can assure you I would do my best although dare I say going to the ICGS is the best way for people to lodge complaints."