The Betis fans at Estadio Benito Villamarin may have ensured the visitors were met by a hostile atmosphere, but Cristiano Ronaldo soon silenced them as his unstoppable effort gave the Madrid club a 10th-minute lead.
Bale added a second before the half-hour mark as he expertly buried a free-kick before Karim Benzema, Angel Di Maria and substitute Alvaro Morata also netted to complete a resounding win that saw Madrid draw level on points with Barcelona and Atletico Madrid at the top of La Liga.
Ancelotti was understandably delighted with his side's "great" performance in Andalusia and acknowledged Bale's impressive display.
"Bale performed well," he said. "But so did everyone else in the team. There was big pressure in the beginning. But everything went well, so we have to be happy.
"When we scored the first goal, the game changed. We had more spaces - it's normal that Betis attacked trying to get a draw.
"All the team played well, we had lots of chances to score – it was a great match from our point of view."
Ancelotti confirmed in the build-up to the match that Morata would not be departing the club on loan in January, with Arsenal reportedly interested, and the Spain Under-21 international admitted he is happy to remain in the Spanish capital.
"Things were easy after Ronaldo's goal," he added.
"But it was a crucial game for us as we were playing before Atletico Madrid and Barcelona.
"I'm very happy here, I belong here. I am delighted to be here even if I get few minutes."
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