How did Tim Allen become the voice of Buzz Lightyear in the Toy Story movies ?

You act as if those aren't any big deal.

Allen's show Home Improvement was usually in the Top 5 shows throughout its entire 8-year run. The Santa Clause movie did extremely well. In addition, Allen was a successful stand-up comic and author.

In fact, there was one week where Tim Allen had the #1 rated TV show, #1 selling movie and #1 selling book.

I think that's worthwhile enough to earn him the Buzz Lightyear role.

DISNEY EXEC: Hey Tim, wanna be the voice of Buzz Lightyear in our new movie "Toy Story"?
TIM ALLEN:......Yeah, ok, sounds like some fun.

That's how.

Disney liked his voice obviously

He wasn't the first choice, originally they wanted Billy Crystal. Home Improvement was produced/distributed by companies that were under the Disney umbrella, so it wasn't that much of a stretch.

If only people asking questions on here also had access to the rest of the internet...

He spoke into a microphone at a sound studio and voila!

Because he was the only person suitable enough for the role of Buzz Lightyear

He has a great voice

No one can say "To Infinity and Beyond" quite as good.

Talent. The word that scares the average asshole leftist to death.
Accomplishment another one.
Winning the worst one.

He got hired for the part. He's perfect for it. Love that character.

Since he did Tim Taylor on Home Improvement and Scott Calvin/Santa Claus in The Santa Clause and its two sequels.

Maybe he auditioned for it and was considered the best.