Ex-Laker Kareem Rush -- Sings 'Stay With Me' ... From His Kitchen

Coming to you from his kitchen ... in a tank top ... former L.A. Lakers baller Kareem Rush singing Sam Smith's "Stay With Me" -- and dude can definitely hit the high note!

As we previously reported, Rush is laser focused on growing his music career -- something he's been passionate about for years. In fact, Rush dropped a single back in 2010.

Now, with a new album on the way ... Rush put his pipes on display on "TMZ Hollywood Sports" -- busting out a ridiculously tough song with no warm-up, no backing track and only basement level acoustics.