Donovan has agreed a two-month loan deal with Everton.
Arena said on his club's website: "This is a great opportunity for Landon.
"During the final months of the 2011 season he was limited because of an ongoing injury and he just started to get his legs back during the play-offs. Therefore, I think that this opportunity with Everton comes at a perfect time as he is rested and ready to go.
"We wish Landon and Everton the very best and look forward to Landon returning to the Galaxy on February 26."