diff --git a/Changes b/Changes
index 833ad2edb..ff846e6eb 100644
--- a/Changes
+++ b/Changes
@@ -137,6 +137,9 @@ Working version
 
 ### Standard library:
 
+- #9865: add Format.pp_print_seq
+  (Raphaël Proust)
+
 - #9781: add injectivity annotations to parameterized abstract types
   (Jeremy Yallop, review by Nicolás Ojeda Bär)
 
diff --git a/stdlib/.depend b/stdlib/.depend
index ffaa61937..2d17694f1 100644
--- a/stdlib/.depend
+++ b/stdlib/.depend
@@ -258,6 +258,7 @@ stdlib__format.cmo : \
     stdlib__string.cmi \
     stdlib.cmi \
     stdlib__stack.cmi \
+    stdlib__seq.cmi \
     stdlib__queue.cmi \
     stdlib__list.cmi \
     stdlib__int.cmi \
@@ -269,6 +270,7 @@ stdlib__format.cmx : \
     stdlib__string.cmx \
     stdlib.cmx \
     stdlib__stack.cmx \
+    stdlib__seq.cmx \
     stdlib__queue.cmx \
     stdlib__list.cmx \
     stdlib__int.cmx \
@@ -278,6 +280,7 @@ stdlib__format.cmx : \
     stdlib__format.cmi
 stdlib__format.cmi : \
     stdlib.cmi \
+    stdlib__seq.cmi \
     stdlib__buffer.cmi
 stdlib__fun.cmo : \
     stdlib__printexc.cmi \
diff --git a/stdlib/format.ml b/stdlib/format.ml
index 2ed7bc6db..f1992924b 100644
--- a/stdlib/format.ml
+++ b/stdlib/format.ml
@@ -1191,6 +1191,22 @@ let rec pp_print_list ?(pp_sep = pp_print_cut) pp_v ppf = function
     pp_sep ppf ();
     pp_print_list ~pp_sep pp_v ppf vs
 
+(* To format a sequence *)
+let rec pp_print_seq_in ~pp_sep pp_v ppf seq =
+  match seq () with
+  | Seq.Nil -> ()
+  | Seq.Cons (v, seq) ->
+    pp_sep ppf ();
+    pp_v ppf v;
+    pp_print_seq_in ~pp_sep pp_v ppf seq
+
+let pp_print_seq ?(pp_sep = pp_print_cut) pp_v ppf seq =
+  match seq () with
+  | Seq.Nil -> ()
+  | Seq.Cons (v, seq) ->
+    pp_v ppf v;
+    pp_print_seq_in ~pp_sep pp_v ppf seq
+
 (* To format free-flowing text *)
 let pp_print_text ppf s =
   let len = String.length s in
diff --git a/stdlib/format.mli b/stdlib/format.mli
index 00aae3653..79a716f53 100644
--- a/stdlib/format.mli
+++ b/stdlib/format.mli
@@ -1084,6 +1084,19 @@ val pp_print_list:
   @since 4.02.0
 *)
 
+val pp_print_seq:
+  ?pp_sep:(formatter -> unit -> unit) ->
+  (formatter -> 'a -> unit) -> (formatter -> 'a Seq.t -> unit)
+(** [pp_print_seq ?pp_sep pp_v ppf s] prints items of sequence [s],
+  using [pp_v] to print each item, and calling [pp_sep]
+  between items ([pp_sep] defaults to {!pp_print_cut}.
+  Does nothing on empty sequences.
+
+  This function does not terminate on infinite sequences.
+
+  @since 4.12
+*)
+
 val pp_print_text : formatter -> string -> unit
 (** [pp_print_text ppf s] prints [s] with spaces and newlines respectively
   printed using {!pp_print_space} and {!pp_force_newline}.