Mr Srivaddhanaprabha died in a helicopter crash on Saturday night after Leicester’s game with West Ham.
Mahrez, who left Leicester for Manchester City in the summer, scored in the 1-0 win over Tottenham on Monday.
He celebrated by raising his hands to the heavens in tribute to Mr Srivaddhanaprabha and the four other victims of the crash.
And Mahrez says he owes a lot to the late billionaire.
“It has been very, very difficult for me,” he said.
“It is not easy to have this type of stuff.
“The Boss was very special to me. I spent four-and-a-half years there and have many memories with him. He was such a good person.
“I am very, very sad. That is why when I scored I put my hands in the sky for him.
“He did a lot for me and Leciester and it is difficult to speak about. It it is very sad.
“He was like a dad. He was very special.
“He was such a good person, a big heart and it was heart-breaking and shocking for me to hear this news and for all of the other people who died with him.
“It is a difficult situation. I am with Leicester and the family of the victims.”
Asked how long it took Mahrez to decide if he would play tonight, he said: “I always wanted to play.
“I know he would have wanted me to play. He was passionate about football.
“It was difficult (to play against Tottenham) but I kept thinking about him. It was difficult to sleep as well.”
Former Leicester manager Claudio Ranieri, who took the Foxes to the Premier League title in 2016, spoke to Italian TV about the incident.
“I was terribly shaken by the news,” Ranieri told Sky Sport Italia.
“He was a good man and always had a positive word for everyone. His positivity and ability to make everybody love him was clear for all to see. He came into the locker room only to dispense kind words, never to reproach you.
“One time soon after my birthday, he arrived in the locker room with a huge cake and made everyone sing ‘Happy Birthday.’
“He was an illuminated man and everything he touched became better.”
Ranieri, who is out of work after leaving Nantes earlier this year, called on Mr Srivaddhanaprabha’s son – Aiyawatt – to continue on from his father.
“Now it’s up to his son, who has always been in love with football, to carry on in his father’s footsteps,” Ranieri said.
“I remember when we first met that I immediately thought he was a positive person, full of energy.
“My objective when I arrived at Leicester was to secure Premier League safety, then we all know what happened.
“Vichai Srivaddhanaprabha made a very important contribution to the Premier League victory, as he’d arrive 30 minutes before the game to embrace everyone.
“He never said a word out of turn, was always happy with a smile on his face.
“I am so sad right now, I want to join the family in their grief.”
