How to center my objects within the artboard without losing their relative positions?

Here’s what I do:

1. Select all on the artboard
2. Cmd + X to Cut
3. Cmd + 0 to center the artboard on the screen
4. Cmd + V to Paste
5. Deselect

Notes:

• Substitute Ctrl for Cmd if you are on Windows
• Paste always pastes to the center of the screen. When the artboard is in the center of the screen (there are multiple ways to do this), then Paste will paste to the center of the artboard.

codo uoc,

But when I checked the if the centering was right, it wasn't, I don't know why;

What happens if you create add rectangle a bit larger than the Group, then align to that?

Alignment is fundamentally about centre (or edge) of Bounding Box, and it may often look and therefore be wrong, especially for shapes/collections that are irregular/far from rectangle/circle; you can see it with a triangle.

You may use such a rectangle and align to that, then adjust the Group within it so it looks/is right, then include the rectangle in the Group after setting its stroke and fill to None, then align/centre to Artboard.

Concerning further work, you may either use the Direct Selection Tool (many use that most of the time in any case) with ClickDragging or Alt/OptionClick, or you can Ungroup (if you need to align/centre again, you can go through the above grouping/internal alignment again).